
==== Front
Int J Sports Phys Ther
Int J Sports Phys Ther
2159
International Journal of Sports Physical Therapy
2159-2896
NASMI Website: International Journal of Sports Physical Therapy

38179585
90284
10.26603/001c.90284
Original Research
Effect of a Novel Training Program in Patients With Chronic Shoulder Pain Based on Implicit Motor Learning: Pilot and Feasibility Study.
Maenhout Annelies
Heijenk Wieger
Glashouwer Peter
Quatacker Lore
Praet Luna
Borms Dorien
Corresponding author: Annelies Maenhout, PhD, PT Department of Rehabilitation Sciences Ghent University De Pintelaan 185, 9000 Ghent, Belgium Phone number: 0032 3320268 Email: annelies.maenhout@ugent.be
1 1 2024
2024
19 1 15031515
2 2 2023
30 10 2023
© The Author(s)
https://creativecommons.org/licenses/by-nc/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial License (4.0) which permits non-commercial use, distribution, and reproduction in any medium, provided the original author and source are credited.

Background

Implicit motor learning has been shown to be effective for learning sports-related motor skills. It facilitates automaticity of movements and thereby improves performance in multitasking and high-pressure environments. Motor learning to develop motor skills and neuroplastic capacities is not sufficiently incorporated in musculoskeletal rehabilitation. Especially in patients with chronic pain conditions like shoulder pain this approach might benefit over traditional exercise programs.

Purpose/hypothesis

The aim of this study was to investigate the feasibility and clinical outcome of a new implicit motor learning exercise program in a group of patients with chronic shoulder pain.

Study design

Pilot and feasibility cohort study

Methods

Twenty-six patients with chronic shoulder pain performed a 6-week home exercise program with weekly remote follow up by a physiotherapist. The program comprised five exercises designed to challenge overall body balance, simultaneously engaging the upper limbs in a range of reaching tasks. The tasks included reaching above the head, at and below waist level, in various directions. No instructions on correct performance were provided to foster external focus. Feasibility was assessed by (1) recruitment rate, (2) follow up rate, (3) subjective experience, (4) self-reported adverse events and (5) self-reported adherence of subjects. Clinical effects of the program were assessed with (1) the Shoulder Pain and Disability Index (SPADI), (2) the Auto-Constant score, (3) the numeric rating scale (NRS) at rest and at night, (4) the patient specific functional scale (PSFS), (5) the avoidance endurance questionnaire (AEQ), (6) patient acceptable symptom state (PASS) and (7) a global rating of change (GROC).

Results

The study protocol was feasible in terms of follow up rate (16w for 28 patients), exercise adherence (77.1%± 29.41), and adverse events (no serious, 5 light adverse events). Statistically significant improvements were observed for SPADI (p<0.001), NRS at rest (p=0.033), at night (p=0.29), PSFS (p<0.001) and PASS (p<0.001) after only six weeks training.

Conclusion

This study reveals promising results of another way of looking at exercise for patients with chronic shoulder pain. Both feasibility and clinical effects of the program on pain and function was acceptable. Future studies should incorporate a control group, provide longer follow up and include objective measurements.

Level of evidence

2b

motor control
chronic shoulder pain
rehabilitation
exercise
telerehabilitation
==== Body
pmcINTRODUCTION

Shoulder disorders are the third most common musculoskeletal disorder after low back and neck pain.1,2 When shoulder pain becomes chronic, it may seriously impair work and leisure participation, disturb sleep, and decrease health-related quality of life.3,4 A conservative approach including exercise is the mainstay in the treatment of chronic shoulder complaints.5,6 Although exercise therapy has proven its effectiveness in chronic musculoskeletal pain there is still a lot unknown about which approach is best for conditions of the shoulder.7 Exercise programs mainly focus on scapular posture, scapular/rotator cuff strengthening, and anterior/posterior shoulder stretching.

Besides improving posture and increasing strength and range of motion, it might be important to prescribe exercises to optimize movement behavior in patients with chronic shoulder pain. Hodges and Tucker8 reported changes at multiple levels of the motor system in patients with chronic pain resulting in altered movement behavior with the objective to ‘’protect’’ the tissues from further pain or injury, or threatened pain or injury. These long-lasting neuromuscular adaptations in response to pain may offer short-term benefit, but have potential long-term consequences due to factors such as increased load, decreased movement, and decreased variability and are advised to address in patients with chronic musculoskeletal pain.8–10 In the majority of clinical practice, patients are provided with explicit guidance for proper movement when retraining motor control. This guidance commonly pertains to coordinating the movements of the patient’s body, including instructions on scapular posture and muscle recruitment. A small alteration in the wording of instructions can result in a substantial influence on both performance and motor learning outcomes. When patients are directed to focus their attention on how their movements affect the environment—an external focus of attention—it leads to more effective and efficient movements.11,12 A movement pattern is considered more efficient or economical if the same movement outcome is achieved with less energy expended. In contrast, directing attention internally towards one’s own movements results in a more conscious form of control that limits the motor system and disrupts automatic control processes.13 The aim of implicit motor learning methods is to minimize the amount of explicit knowledge about movement execution and/or muscle recruitment during learning (internal focus), reduce the reliance on the working memory, and promote a more automatic control process.14

Implicit learning is an approach in which self-organization is key. The principle of self-organization emphasizes that coordinated movements emerge naturally from the interactions among the components of the motor system. Instead of being rigidly controlled from outside, the body adapts and organizes itself to achieve task goals while exploring different movement patterns. This concept highlights the importance of allowing learners to explore and discover their own movement solutions, promoting adaptability and skill development. In sports science, there is increasing evidence that implicit motor learning is superior to explicit learning when it comes to learning new skills and improving performance.15,16 There are a number of disciplines in which implicit learning has been successfully applied, including pediatric physiotherapy, gait training for stroke patients, and ACL rehabilitation, but implicit learning is rarely used in the context of shoulder rehabilitation.14,17,18

Considering the expected duration of rehabilitation within chronic shoulder pain patients, telerehabilitation seems a suitable medium for this population.19 During the COVID-19 pandemic physiotherapists widely used telerehabilitation to coach patients in their home exercise programs. In systematic reviews, both Seron et al. and Gava et al. concluded that telerehabilitation could be comparable to in-person rehabilitation to reduce pain and improve physical function in musculoskeletal conditions generally and shoulder pain specifically, but more high quality research is needed.20,21 The main advantage of telerehabilitation is that both the healthcare professional and the patient can carry out the treatment in their own environment without travel time or necessary transport.

The promising results of implicit motor learning in other conditions and the possibility of implicit learning to change motor control deficits evidenced in chronic pain conditions gave rise to this study. The aim of this study was to investigate the feasibility and clinical outcome of a new implicit motor learning exercise program in a group of patients with chronic shoulder pain.

MATERIALS AND METHODS

Study design

The feasibility study was a single group pre-post intervention design. The Institutional Review Board of Ghent University Hospital (B.U.N.: B6702020000611) approved the study.

Participants

Adults with chronic shoulder pain were recruited on social media and via flyers in public buildings and physiotherapy practices. Potential candidates were first screened through an online questionnaire to check whether they met inclusion criteria (questions on duration of shoulder pain, the experience of an unstable feeling in the shoulder, dislocations/subluxations, mobility restrictions of the shoulder, results of medical imaging, medical diagnosis). To be included patients had to have had shoulder pain for at least six months for which they consulted a medical doctor (MD). Participants were excluded if they were currently in therapy or had undergone shoulder surgery or sustained a shoulder fracture. Moreover, patients that were expected not to benefit the intervention were excluded namely patients with an unstable shoulder (shoulder dislocation/instability, labral lesion), capsular stiffness (frozen shoulder, severe osteoarthrosis) or with inflammatory nociceptive pain mechanisms (bursitis, calcific tendinopathy, rheumatic disorders), as diagnosed by the MD, were excluded. All participants signed an informed consent prior to participation.

Outcomes

Feasibility outcomes consisted of recruitment rate, follow up rate (% of participants who successfully completed the program and were reevaluated after six weeks), subjective reports regarding experience with the content of the program (custom-crafted statements on the content of this program scored with Likert scale eg. “I understood what was expected”, “I thought the exercises were easy to do”), self-reported adverse events, and self-reported adherence. Adherence was scored weekly as 0 (did not meet minimal exercise adherence of 15’, 3x/week) or 1 (meets minimal exercise adherence of 15’, 3x/week). A score of six out of six (100%) was defined as perfect adherence. Based on this outcome the feasibility of a future RCT and the need for protocol modification were assessed.

At baseline and after the six-week home exercise program patients were requested to complete an online questionnaire package that consisted of demographic variables and several patient reported outcome measures (PROMs). Pain and function were evaluated with the Shoulder Pain and Disability Index (SPADI)22 and Auto-Constant score.23 The SPADI was chosen due to excellent reported reliability (ICC≥0.90) in most studies, with reported minimal detectable change (MDC) of 18 points and minimal clinically important difference (MCID) between 8 and 13 points.24,25 The Auto-Constant score (patient self-report based) and the Constant score (clinician-based) have been shown to correlate well but no information on test-retest reliability of the Auto-Constant score is available.23,26 This alternative to the Constant score allows remote assessment which was necessary at the time of the study due to COVID precautions. Self-perceived active mobility and strength was measured with the Auto-Constant score. In this questionnaire patients have to select the pictures of a person lifting a weight or performing a specific movement that correspond with the level of lifting or moving they estimated themselves to be capable of.23 To assess patterns of fear-avoidance and endurance-related responses to pain the Avoidance Endurance Questionnaire (AEQ) was used.27 According to Hasenbring et al.,27 inactive, avoidant behavior would drive disuse-related muscle weakness, deconditioning, and metabolic changes in the musculoskeletal structures and the central nervous system, potentially leading to peripheral and central sensitization and increased pain perception. In contrast, in overactive behavior, inappropriate muscle forces might expose mainly passive structures (vertebral joints, ligaments, connective tissue) to increased stress and repetitive strain, causing microdamage, laxity, and inflammation. The AEQ was developed to assess emotional, cognitive, and behavioral fear-avoidance and endurance responses to pain, and has been validated and repeatedly applied in different chronic pain populations.27–29 This self report questionnaire consists of three parts (pain affective, cognitive and behavioural responses). More detailed information on the subscales of the AEQ can be found in Appendix 2.

Each item was scored on a 7 point-Likert scale (0: never, 1: almost never, 2: seldom, 3: sometimes, 4: often, 5: most of the time, and 6: always). Higher scores represent more thoughts that correspond with avoidance or endurance of pain. All subscales Chronbach’s alpha were in range from 0.76 to 0.91, which showed acceptable internal consistency.27 The participants were asked to fill out the questionnaire considering the pain they experienced in the past 14 days.

Overall satisfaction with the shoulder condition was evaluated before and after the 6-week program with the Patient Acceptable Symptom State (PASS).30 After the program patients were asked to score the rate of change between -5 and 5 (Global rating of change (GROC).31,32 A score of -5 corresponds with shoulder complaints being a lot worse than before the program, 0 with no change, and 5 with full recovery of shoulder complaints. A systematic review and meta-analysis on measurement properties concluded that GROC shows excellent test-retest reliability (ICC = 0.84) but as recall bias might influence validity it is advised to combine with other outcomes to track changes in symptoms.33

During weekly follow up, patients were asked to rate their pain at rest and at night on a numeric rating scale (NRS) as well as their ability to perform three important functional activities, using the Patient Specific Function Scale (PSFS).34,35 For NRS MCID was found to be 2.17 points in a population with shoulder pain.36 The PSFS shows moderate to good test-retest reliability (ICC 0.71) and MCID was shown to be 1.2 points.35 The advantage of the PSFS is that each patient can rate functional ability during daily life tasks that are relevant for them.

Intervention

For specific content reporting of the home based exercise program the Consensus on Exercise Reporting Template was followed.37 A general instruction video (https://youtu.be/s11NShRi35Y) and videos with exercise instructions (Appendix 1) were accessible online.

The program consisted of five exercises (Figure 1 and Appendix 1 detailed instructions). The exercise program was based on the principles of implicit motor learning.38

187253 Figure 1. Home exercise program

Self organization

To elicit unconscious automatic bottom-up organization of motor control of the upper extremities, overall balance was challenged during the exercises.38 Each exercise had ten levels of difficulty to maintain total body balance (Appendix 1). To determine the level at the start, the 70-30% rule was used. Participants were instructed to select the level at which they could execute the exercise approximately seven out of ten times without losing balance.

To encourage participants to expand their range of motor control possibilities and engage their shoulder muscles beyond their comfort zone, they were consistently prompted to reach their maximum extent during all exercises. While performing the exercise, individuals should exert additional effort to reach the target and fully utilize their shoulder mobility. To achieve this, subjects were directed to position themselves in a manner where the target was placed just beyond their normal reach.

External focus instructions

During all exercises the focus was on the target (sliding objects over the floor, reaching towards the wall, touching toes) and no instructions were provided on how to perform the exercise. To correct performance in case of discomfort or low back pain for example analogies were used to elicit the desired movement behavior implicitly throughout the program such as for example: “imagine your legs both in a cast as you perform the exercises, now imagine that your legs are out of the casts” or “imagine your legs stuck in concrete, now the concrete is broken and you are free again”.

Self-controlled learning and enhanced expectations

In the majority of rehabilitation scenarios, clinicians typically dictate the specifics of the training session. This includes decisions about the sequencing of tasks, the duration of practice, and when or whether instructions or demonstrations are provided. Consequently, patients often play a relatively passive role, with clinicians maintaining general control over most practice aspects. However, self-controlled learning, such as allowing patients to have some influence, requesting feedback, or selecting exercises, emerges as a potent instrument in the realm of motor learning. From a motivational perspective, patients were encouraged by the therapists (two last year master physiotherapy students that were specifically trained and under the supervision of two experienced senior shoulder physiotherapists) to take maximal responsibility in their training program and received the autonomy to make choices.13,39 During the six weeks participants were asked to practice with a minimum of three times a week. The therapists suggested that there may be superior outcome if the patients practiced more than three times per week. Duration of one exercise session was instructed to be 15 to 20 minutes but participants were allowed to perform shorter sessions multiple times a day. The sequence and duration of each exercise was not set. Participants could choose when and how much a specific exercise was done as long as a total of 15-20 minutes was reached. To control the pain (during and immediately after exercise, day to day, and week to week), participants were instructed to follow the pain monitoring model (Appendix 1).40,41 When pain increased or fatigue began, participants were instructed to switch to another exercise.

Follow-up with the participants was provided by the therapists during a weekly video or phone call according to individual preference. During these calls pain, PSFS, the level of difficulty achieved for each exercise (and whether this was challenging enough), adverse events, and the frequency and duration of training sessions were discussed.

Statistical analysis

Data were analyzed with SPSS statistical software (IBM SPSS Statistics, Version 27.0). Descriptive statistics were used to assess the feasibility outcomes. A Shapiro-Wilk test was combined with a histogram to check normal distribution. Paired sample t-tests and Wilcoxon signed-rank tests were used to compare SPADI, AEQ, Auto-Constant scores and NRS at rest, at night, and during patient specific activities (PSFS) pre to post. Differences in the PASS were analyzed with a McNemar test. Statistically significant differences were considered at p<0.05. Post hoc power analysis was conducted based on the SPADI.

RESULTS

A group of 28 participants (Mean age= 34.9 years ±13.59; male/female= 10/17) was recruited. Baseline characteristics are summarized in Table 2. Medical diagnoses of their shoulder pain differed among the group most of which were related to the rotator cuff (shoulder impingement, subacromial impingement, rotator cuff related shoulder pain, subacromial pain syndrome, rotator cuff tendinopathy, rotator cuff muscle “sprain”) however, some patients did not have clear medical diagnoses (such as “functional shoulder pain”). Twenty-six patients completed the study and two were lost to follow-up (one spontaneous improvement of pain before start of the study and one decided to consult an orthopedic surgeon for second opinion).

Feasibility outcome

Recruitment rate: A total of 16 weeks was required to screen 96 patients of which 28 patients met the inclusion criteria and were eligible for participation in this study.

Follow up rate: 92.9% of participants successfully completed follow up assessment after 6 weeks.

Subjective experience with the content of the program: The outcome of the questions regarding the personal experience of the exercise program is visualized in Figure 2. Majority of participants (66.6%) indicated their expectations regarding the exercise program were fulfilled. Therapist guidance, follow up and content of the exercise program received positive feedback from all participants. Moreover, 62.9% of participants felt the exercise program had positive effects on their shoulder pain.

Self-reported adverse events: Five patients reported adverse events during performance of exercises: low back pain (n=3), groin pain (n=1) and knee pain (n=1). All could be resolved by providing information on correct performance of the exercises or adapting the exercises. No patients reported adverse events after completion of the study.

Self-reported adherence: The mean adherence to the exercise program was 77.1 ± 29.41%. It can be observed in Figure 3 that the adherence was higher during the first two weeks, decreased after that, and increased again towards the end of the program.

187254 Figure 2. Personal experience regarding the exercise program (expressed as the percentage of participants in each answer category)

187255 Figure 3. Mean adherence (percentage) over 6 weeks (100% equals exercising as prescribed at least 3 days a week, at least 15 minutes)

Effect of the program on PROMs

An overview of the pre- and post-intervention scores for the PROMs and the corresponding p-values are presented in Table 1. Post hoc power analysis based on the SPADI resulted in a power of 0.94.

187256 Table 1. Patient reported outcome measurements before and after the intervention.

	Pre (mean ± SD)	Post (mean ± SD)	p-value	
SPADI	Pain	36.0 ± 21.50	20.8 ± 19.21	<0.001*	
	Function	26.6 ± 20.81	14.6 ± 16.81	<0.001*	
	Total	31.3 ± 20.25	17.7 ± 17.75	<0.001*	
Auto-Constant	Pain	6.7 ± 3.07	3.8 ± 2.98	<0.001*	
	Strength	14.4 ± 4.97	17.1 ± 5.32	0.008*	
	ROM	16.5 ± 4.81	19.3 ± 3.46	0.001*	
	Activity	12.8 ± 2.06	13.3 ± 1.76	0.168	
	Total	50.5 ± 8.52	53.4 ± 5.43	0.060	
PASS		0.2 ± 0.43	0.7 ± 0.47	<0.001*	
AEQ: pain emotional reactions	ADS	1.5 ± 1.02	0.9 ± 0.82	<0.001*	
	PMS	4.2 ± 1.52	4.7 ± 0.82	0.007*	
AEQ: pain cognitive reactions	HHS	2.1 ± 1.31	1.4 ± 1.12	0.002*	
	CTS	0.5 ± 0.89	0.4 ± 0.69	0.471	
	TSS	2.7 ± 1.37	2.8 ± 1.44	0.737	
AEQ: pain coping reactions	APAS	1.3 ± 0.98	1.3 ± 0.87	0.951	
(light pain)	ASAS	1.5 ± 0.55	1.4 ± 0.42	0.169	
	PPS	2.5 ± 0.75	2.6 ± 0.74	0.340	
	HDS	2.9 ± 0.98	2.8 ± 0.75	0.700	
	BES (PPS + HDS)	5.4 ± 1.55	5.4 ± 1.32	0.859	
AEQ: pain coping reactions	APAS	1.7 ± 0.57	1.4 ± 0.81	0.089	
(severe pain)	ASAS	2.1 ± 0.48	2.0 ± 0.46	0.146	
	PPS	3.0 ± 0.90	2.9 ± 1.02	0.615	
	HDS	3.0 ± 1.26	3.2 ± 1.25	0.475	
	BES (PPS + HDS)	6.1 ± 1.93	6.1 ± 2.00	0.895	
NRS	Pain @ rest	1.8 ± 1.68	1.2 ± 1.91	0.033*	
	Pain @ night	1.9 ± 2.05	1.1 ± 1.94	0.029*	
	PSFS	4.6 ± 1.73	2.3 ± 2.00	<0.001*	
* indicates a statistically significant change at p<0.05; SD = Standard Deviation; SPADI= Shoulder Pain and Disability Index; ROM= Range of Motion; PASS= Patient Acceptable Symptom State; AEQ= Avoidance-Endurance Questionnaire; ADS = Anxiety Depression Scale; PMS= Positive Mood Scale; HHS= Help Hopelessness Scale; CTS= Catastrophizing Thoughts Scale; TSS= Thought Suppression Scale; APAS= Avoidance of Physical Activities Scale; ASA= Avoidance of Social Activities Scale; PPS= Pain Persistence Scale; HDS= Humor Distraction Scale; BES= Behavioral Endurance Scale; NRS= Numeric Rating Scale; PSFS= Patient Specific Function Scale.

SPADI pain scores were significantly lower after six weeks of training (median difference [95%CI]= -14.0 [-22.0; -7.0]; p<0.001). SPADI function scores were significantly improved after the exercise program (median difference [95%CI]= -10.0 [-15.0; - 5.6]; p<0.001). Total SPADI scores improved significantly (mean difference [95%CI]= - 13.6 [-19.8;-7.4]; p<0.001).

In the Auto-Constant questionnaire, significant improvement was attained for pain, self-perceived strength, and ROM. The pain scores decreased significantly (median difference [95%CI]= -3.0 [-4.5; -1.5]; p<0.001), strength scores increased significantly (median difference [95%CI]= 2.5 [0.0; 5.0]; p=0.008) and ROM scores improved significantly (median difference [95%CI]= 2.0 [1.0; 3.5]; p=0.001). Activity scores did not change significantly (mean difference [95%CI]= 0.5 [-0.2; 1.2]; p=0.168) and the total Auto-Constant score was not significantly different after intervention (mean difference [95%CI]= 3.0 [-0.1; 6.1]; p= 0.060).

Before the program, 23.1% of the participants was satisfied with their shoulder condition, whereas after the study 69.3% were satisfied as measured with the PASS. This proportional change was significant (p<0.001).

The mean NRS pain score at rest improved significantly through the research (median difference [95%CI]= -0.5 [-1.5; 0.0]; p=0.033) as did the pain scores at night (median difference [95%CI]= -0.8 [-1.5; 0.0]; p= 0.029). For the PSFS the participants reported a significantly lower score reflecting improved ability to perform functional activities after the program (mean difference [95%CI]= -2.4 [-3.4;-1.5]; p<0.001).

Regarding the AEQ, the Pain Emotional Reactions score improved significantly after the intervention. The Anxiety Depression Scale (ADS) showed a significant mean difference [95%CI] of -0.6 [-0.8;-0.3] (p<0.001). Additionally, the Positive Mood Scale (PMS) significantly improved after training with a median difference [95%CI] of 0.5 [0.2; 1.0] (p=0.007). For the subscale Pain Cognitive Reactions, only the Help Hopelessness Scale (HHS) reached a significant difference (mean difference [95%CI]= -0.7 [-1.0;-0.3]; p= 0.002).

The self-perceived change in the condition of the shoulder after six weeks of exercising as measured with the GROC showed a mean change of 1.9 points (±1.89). The distribution of the scores are presented in Figure 4.

187257 Figure 4. Global rating of change

A score of -5: shoulder complaints a lot worse than before the program, 0: no change, 5: full recovery of shoulder complaints

DISCUSSION

The aim of this research was to determine whether a novel home exercise program conducted via telerehabilitation based on implicit motor learning was effective for patients with chronic shoulder pain and whether the study protocol was feasible. The results showed that the study protocol was feasible in terms of follow up rate, exercise adherence, and adverse events. Statistically significant improvements were observed for the SPADI, NRS at rest and at night, and PASS after only six weeks training.

Twenty-six participants completed the six-week exercise program at home with weekly remote follow-up. The results showed that the study protocol was feasible with respect to follow-up rate and acceptable in terms of personal experience with the program, exercise adherence and adverse events. Majority of participants (66.6%) indicated their expectations regarding the exercise program to be fulfilled. Therapist guidance, follow up, and content of the exercise program received positive feedback from all participants. Moreover, 62.9% of participants felt the exercise program had positive effects on their shoulder pain. This is an important finding, since perception of participants about the exercise program is crucial for adherence to the treatment and thus successful rehabilitation.42,43 Although patient and therapist never met in person due to COVID-19 measures, participants indicated that they understood the instructions on the phone or video-calls, when combined with the YouTube videos.

Frequency of follow-up also appeared important in view of adverse events. Providing instructions on how to adapt the exercises was key in preventing pain in other joints such as low back and knee to persist. Hence, the communication used in this study appeared suitable for telerehabilitation.

The clinical outcome results are very promising after only six weeks of training. There was a 13.6 point decrease in the primary outcome (SPADI score). This result is higher than the MCID of 8-13 points but lower than the MDC of the SPADI of 18 points.24 The magnitude of this difference is comparable to other studies investigating the effect of more traditional exercise programs with strength and mobility exercises.44,45 Littlewood et al. for example showed improvement of SPADI scores after three months with 12.4 points in the self-managed group and 16.7 points in the usual physiotherapy group in patients with subacromial pain syndrome.45 Especially considering the study population (>6 months shoulder pain) a longer duration is recommended given that earlier research indicated longer lasting complaints may require a prolonged rehabilitation.46 The improvement in pain was significant for pain at rest and at night. The amount of change was smaller than the MCID of 2.17 points but comparable to changes seen in other intervention studies in this population.47,48 It is important to note that the small improvement might also be related to the rather low pain scores at baseline (1.8-1.9) which is most likely the result of exclusion of serious shoulder pathology such as frozen shoulder in the current study. A mean change in shoulder complaints of 1.9 points on the GROC represents that participants consider the change valuable regarding their health status.31

After the program it was shown that pain emotional reactions, as measured with the AEQ, significantly improved, meaning that patients had fewer depressive thoughts and anxiety and were in a better mood. This may relate to a happier lifestyle and thus a higher quality of life. In contrast, no significant changes were seen in participant’s coping reactions. Pain cognitive reactions also did not change significantly except for the HHS. The HHS represents the lack of hope and the feeling of impossibility to become pain-free.49 In other words, participants believed in the advantages of exercising and had a more optimistic point of view on the future after study completion. Combining the exercise program with behavioral change techniques could be an interesting direction for future research.

The current study attained a high percentage of compliance of 77%. Compared to other studies this adherence rate with home-based training was rather high. For example, Burns et al.43 reported an adherence of 41% with a home exercise program for patients with rotator cuff pathology. Possible reasons for this strong adherence might be the weekly follow-up calls, the dynamic nature of the exercises and the freedom of planning practice. Freedom of planning their own practice was perceived as an advantage by 96% of participants. Rehabilitation outcome strongly depends on treatment adherence. Interestingly, in this study it was observed that adherence decreased to the lowest value at week four and then started improving again towards the end of the program. A potential cause for the motivational dip could be that the novelty of the exercises was gone, and the end of the training period still seemed a long way off. NRS scores at rest and at night increased between week four and five probably causing the participants to see the benefit of the exercise program which in turn increased the adherence. After six weeks of training 70.4% of participants indicated they planned to continue to perform the exercises after study completion. The setup of this study with a home-based program and maximal responsibility for patients might be advantageous for patients’ self-efficacy, autonomy, and active coping behavior.

The training program only consisted of exercises based on implicit motor learning with external focus, no manual therapy or strength training was included. The underlying mechanism that could explain the clinical improvements might be related to motor learning resulting in more efficient and less rigid movement patterns. Studies investigating EMG muscle recruitment during a variety of exercises comparing external focus of attention to internal focus of attention showed lower muscle recruitment in the first.11,12,50–55 In these studies, where the executed movement remains constant and only the focus of attention is shifted, a decrease in muscle recruitment could indicate enhanced efficiency in performing the exercise. This could be beneficial during functional movements in daily activities. During follow up, some participants spontaneously reported that they noticed starting to use their affected shoulder more during daily activities and a significant improvement was found in their ability to perform individually reported activities as measured with the PSFS. A future study might include objective measurements of arm use in daily life. The placebo effect due to being included in a study and receiving attention from the therapist cannot be out ruled as there was no control group.

Limitations

A first limitation of this study is the lack of a control group. In addition to ruling out the influence of natural recovery, incorporating a control group would provide clarity on how the outcomes of this novel exercise program compare to a conventional function-based program. The latter typically includes a range of isolated shoulder strengthening and mobility exercises.

The second limitation is that no objective data on strength and mobility could be collected due to COVID measures at the time of the study. To evaluate exercise adherence objective data would also be desirable. Since the follow-up calls were not anonymous, socially desirable responses might unconsciously have been encouraged.

Finally, study duration can be considered a limitation. A future trial should have a longer training program of at least 12 weeks and include long term follow-up after six months up to one year.

CONCLUSION

The results of the current study provide promising results of a novel way designing shoulder exercises for patients with chronic shoulder pain. The home-based, six-week exercise program based on implicit motor learning produced significant improvements in pain and function in patients with chronic shoulder pain. The study protocol was feasible in terms of follow up rate, exercise adherence and adverse events. Participants especially appreciated the freedom to plan their exercise sessions and instructions and follow up provided by the therapists. Recruitment rate was rather low. Future studies should incorporate a control group, provide longer follow up, and include objective measurements to analyze changes in strength, range of motion, and use of the affected upper limb during daily life.

Conflict of interest

The authors declare that they have no conflict of interest.

Supplementary Material

Appendix 1

Appendix 2
==== Refs
Incidence of shoulder pain in 40 years old and over and associated factors: A systematic review European Journal of Pain Djade Codjo D. Porgo Teegwendé V. Zomahoun Hervé Tchala Vignon Perrault-Sullivan Gentiane Dionne Clermont E. 2020
24 1 39 50 1090-3801 10.1002/ejp.1482 10.1002/ejp.1482 31514243
Costs of shoulder pain in primary care consulters: a prospective cohort study in The Netherlands BMC Musculoskeletal Disorders Kuijpers Ton van Tulder Maurits W van der Heijden Geert JMG Bouter Lex M van der Windt Daniëlle AWM 1 11 2006
7 1 83 1471-2474 10.1186/1471-2474-7-83 10.1186/1471-2474-7-83 17078883
Avoidable costs of physical treatments for chronic back, neck and shoulder pain within the Spanish National Health Service: a cross-sectional study BMC Musculoskeletal Disorders Serrano-Aguilar Pedro Kovacs Francisco M Cabrera-Hernández Jose M Ramos-Goñi Juan M García-Pérez Lidia 12 2011
12 1 287 1471-2474 10.1186/1471-2474-12-287 10.1186/1471-2474-12-287 22188790
Impaired health-related quality of life, psychological distress, and productivity loss in younger people with persistent shoulder pain: a cross-sectional analysis Disability and Rehabilitation Ackerman Ilana N. Fotis Kathy Pearson Lauren Schoch Peter Broughton Nigel Brennan-Olsen Sharon L. Bucknill Andrew Cross Emily Bunting-Frame Nicola Page Richard S. 2022
44 15 3785 3794 0963-8288 10.1080/09638288.2021.1887376 10.1080/09638288.2021.1887376 33620022
Exercise therapy for chronic pain Physical Medicine and Rehabilitation Clinics of North America Kroll Heather R. 5 2015
26 2 263 281 1047-9651 10.1016/j.pmr.2014.12.007 10.1016/j.pmr.2014.12.007 25952064
A meta-analytic review of the hypoalgesic effects of exercise The Journal of Pain Naugle Kelly M. Fillingim Roger B. Riley Joseph L., III 12 2012
13 12 1139 1150 1526-5900 10.1016/j.jpain.2012.09.006 10.1016/j.jpain.2012.09.006 23141188
Specific versus non-specific exercises for chronic neck or shoulder pain: A systematic review Journal of Clinical Medicine Dueñas Lirios Aguilar-Rodríguez Marta Voogt Lennard Lluch Enrique Struyf Filip Mertens Michel G. C. A. M. Meulemeester Kayleigh De Meeus Mira 18 12 2021
10 24 5946 2077-0383 10.3390/jcm10245946 10.3390/jcm10245946 34945241
Moving differently in pain: a new theory to explain the adaptation to pain Pain Hodges Paul W. Tucker Kylie 3 2011
152 3 Suppl S90 S98 0304-3959 10.1016/j.pain.2010.10.020 10.1016/j.pain.2010.10.020 21087823
Pain and motor control: From the laboratory to rehabilitation Journal of Electromyography and Kinesiology Hodges Paul W. 4 2011
21 2 220 228 1050-6411 10.1016/j.jelekin.2011.01.002 10.1016/j.jelekin.2011.01.002 21306915
Temporal association between changes in primary sensory cortex and corticomotor output during muscle pain Neuroscience Schabrun S.M. Jones E. Kloster J. Hodges P.W. 4 2013
235 159 164 0306-4522 10.1016/j.neuroscience.2012.12.072 10.1016/j.neuroscience.2012.12.072 23357117
Increased jump height and reduced EMG activity with an external focus Human Movement Science Wulf Gabriele Dufek Janet S. Lozano Leonardo Pettigrew Christina 6 2010
29 3 440 448 0167-9457 10.1016/j.humov.2009.11.008 10.1016/j.humov.2009.11.008 20409600
Superiority of external attentional focus for motor performance and learning: Systematic reviews and meta-analyses. Psychological Bulletin Chua Lee-Kuen Jimenez-Diaz Judith Lewthwaite Rebecca Kim Taewon Wulf Gabriele 6 2021
147 6 618 645 1939-1455 10.1037/bul0000335 10.1037/bul0000335 34843301
Optimizing performance through intrinsic motivation and attention for learning: The OPTIMAL theory of motor learning Psychonomic Bulletin & Review Wulf Gabriele Lewthwaite Rebecca 29 1 2016
23 5 1382 1414 1069-9384 10.3758/s13423-015-0999-9 10.3758/s13423-015-0999-9
Principles of Motor Learning to Support Neuroplasticity After ACL Injury: Implications for Optimizing Performance and Reducing Risk of Second ACL Injury Sports Medicine Gokeler Alli Neuhaus Dorothee Benjaminse Anne Grooms Dustin R. Baumeister Jochen 5 2 2019
49 6 853 865 0112-1642 10.1007/s40279-019-01058-0 10.1007/s40279-019-01058-0 30719683
Does implicit motor learning lead to greater automatization of motor skills compared to explicit motor learning? A systematic review PLoS One Kal Elmar Prosée Rens Winters Marinus van der Kamp John 5 9 2018
13 9 e0203591 1932-6203 10.1371/journal.pone.0203591 10.1371/journal.pone.0203591 30183763
Implicit learning increases shot accuracy of football players when making strategic decisions during penalty kicking Human Movement Science Navarro Martina van der Kamp John Schor Paulo Savelsbergh Geert J.P. 10 2018
61 72 80 0167-9457 10.1016/j.humov.2018.07.004 10.1016/j.humov.2018.07.004
Is Implicit Motor Learning Preserved after Stroke? A Systematic Review with Meta-Analysis PLoS One Kal E. Winters M. van der Kamp J. Houdijk H. Groet E. van Bennekom C. Scherder E. 16 12 2016
11 12 e0166376 1932-6203 10.1371/journal.pone.0166376 10.1371/journal.pone.0166376 27992442
Effect of internal versus external focus of attention on implicit motor learning in children with developmental coordination disorder Research in Developmental Disabilities Jarus Tal Ghanouni Parisa Abel Rachel L. Fomenoff Shelby L. Lundberg Jocelyn Davidson Stephanie Caswell Sarah Bickerton Laura Zwicker Jill G. 2 2015
37 119 126 0891-4222 10.1016/j.ridd.2014.11.009 10.1016/j.ridd.2014.11.009
Asynchronous and Tailored Digital Rehabilitation of Chronic Shoulder Pain: A Prospective Longitudinal Cohort Study Journal of Pain Research Janela Dora Costa Fabíola Molinos Maria Moulder Robert G Lains Jorge Francisco Gerard E Bento Virgílio Cohen Steven P Correia Fernando Dias 1 2022
15 53 66 1178-7090 10.2147/jpr.s343308 10.2147/jpr.s343308 35035234
Effectiveness of Telerehabilitation in Physical Therapy: A Rapid Overview Physical Therapy Seron Pamela Oliveros María-Jose Gutierrez-Arias Ruvistay Fuentes-Aspe Rocío Torres-Castro Rodrigo C Merino-Osorio Catalina Nahuelhual Paula Inostroza Jacqueline Jalil Yorschua Solano Ricardo Marzuca-Nassr Gabriel N Aguilera-Eguía Raul Lavados-Romo Pamela Soto-Rodríguez Francisco J Sabelle Cecilia Villarroel-Silva Gregory Gomolán Patricio Huaiquilaf Sayen Sanchez Paulina 9 2 2021
101 6 0031-9023 10.1093/ptj/pzab053 10.1093/ptj/pzab053 33561280
Effectiveness of physical therapy given by telerehabilitation on pain and disability of individuals with shoulder pain: A systematic review Clinical Rehabilitation Gava Vander Ribeiro Larissa Pechincha Barreto Rodrigo Py Gonçalves Camargo Paula Rezende 1 3 2022
36 6 715 725 0269-2155 10.1177/02692155221083496 10.1177/02692155221083496
Measurement properties of translated versions of the Shoulder Pain and Disability Index: A systematic review Clinical rehabilitation Kc Sudarshan Sharma Saurab Ginn Karen A Reed Darren 2021
35 3 410 422 0269-2155 10.1177/0269215520963199 10.1177/0269215520963199 33025826
The “Auto-Constant”: Can we estimate the Constant-Murley score with a self-administered questionnaire? A pilot study Orthopaedics & Traumatology: Surgery & Research Chelli Mikaël Levy Yohann Lavoué Vincent Clowez Gilles Gonzalez Jean-François Boileau Pascal 4 2019
105 2 251 256 1877-0568 10.1016/j.otsr.2018.11.023 10.1016/j.otsr.2018.11.023
Measuring shoulder function: a systematic review of four questionnaires Arthritis Care & Research Roy Jean-Sébastien MacDermid Joy C. Woodhouse Linda J. 29 4 2009
61 5 623 632 0893-7524 10.1002/art.24396 10.1002/art.24396
A comparison of four shoulder-specific questionnaires in primary care Annals of the Rheumatic Diseases Paul A Lewis M Shadforth M F Croft P R Van Der Windt D A Hay E M 1 10 2004
63 10 1293 1299 0003-4967 10.1136/ard.2003.012088 10.1136/ard.2003.012088 15361390
A patient-derived Constant-Murley score is comparable to a clinician-derived score Clinical Orthopaedics & Related Research Levy Ofer Haddo Omar Massoud Samir Mullett Hannan Atoun Ehud 1 2014
472 1 294 303 0009-921X 10.1007/s11999-013-3249-3 10.1007/s11999-013-3249-3 23982405
Fear-avoidance- and endurance-related responses to pain: development and validation of the Avoidance-Endurance Questionnaire (AEQ) European Journal of Pain Hasenbring Monika I. Hallner Dirk Rusu Adina C. 7 2009
13 6 620 628 1090-3801 10.1016/j.ejpain.2008.11.001 10.1016/j.ejpain.2008.11.001 19101182
Psychological pain responses in athletes and non-athletes with low back pain: Avoidance and endurance matter European Journal of Pain Gajsar Hannah Titze Christina Levenig Claudia Kellmann Michael Heidari Jahan Kleinert Jens Rusu Adina Carmen Hasenbring Monika Ilona 19 7 2019
23 9 1649 1662 1090-3801 10.1002/ejp.1442 10.1002/ejp.1442
Translation, reliability, and validity of the avoidance endurance questionnaire in Iranian subjects with chronic non-specific neck pain Journal of family medicine and primary care Karimi Ghasem Abad Sarvenaz Akhbari Behnam Salavati Mahyar Saeedi Ahmad Seydi Mahsa Shakoorianfard Mohammad Ali 2020
9 7 3565 73 2249-4863 10.4103/jfmpc.jfmpc_194_20 10.4103/jfmpc.jfmpc_194_20 33102331
Minimal clinically important improvement/difference (MCII/MCID) and patient acceptable symptom state (PASS): what do these concepts mean? Annals of the rheumatic diseases Kvien T. K Heiberg T. Hagen K. B 1 11 2007
66 Suppl 3 iii40 iii41 0003-4967 10.1136/ard.2007.079798 10.1136/ard.2007.079798 17934093
Global rating of change scales: a review of strengths and weaknesses and considerations for design Journal of Manual & Manipulative Therapy Kamper Steven J Maher Christopher G Mackay Grant 7 2009
17 3 163 170 1066-9817 10.1179/jmt.2009.17.3.163 10.1179/jmt.2009.17.3.163 20046623
Global Rating of Change scales Australian Journal of Physiotherapy Kamper Steve 2009
55 4 289 0004-9514 10.1016/s0004-9514(09)70015-7 10.1016/s0004-9514(09)70015-7 19929778
Psychometric properties of the global rating of change scales in patients with low back pain, upper and lower extremity disorders. A systematic review with meta-analysis Journal of Orthopaedics Bobos Pavlos Ziebart Christina Furtado Rochelle Lu Ze MacDermid Joy C. 9 2020
21 40 48 0972-978X 10.1016/j.jor.2020.01.047 10.1016/j.jor.2020.01.047 32082038
Evaluative measurement properties of the patient-specific functional scale for primary shoulder complaints in physical therapy practice Journal of Orthopaedic & Sports Physical Therapy Koehorst Marije L. van Trijffel Emiel Lindeboom Robert 8 2014
44 8 595 603 0190-6011 10.2519/jospt.2014.5133 10.2519/jospt.2014.5133 25029915
The patient-specific functional scale: validity, reliability, and responsiveness in patients with upper extremity musculoskeletal problems Journal of Orthopaedic & Sports Physical Therapy Hefford Cheryl Abbott J. Haxby Arnold Richard Baxter G. David 2 2012
42 2 56 65 0190-6011 10.2519/jospt.2012.3953 10.2519/jospt.2012.3953
Responsiveness of the numeric pain rating scale in patients with shoulder pain and the effect of surgical status Journal of Sport Rehabilitation Michener Lori A. Snyder Alison R. Leggin Brian G. 2 2011
20 1 115 128 1056-6716 10.1123/jsr.20.1.115 10.1123/jsr.20.1.115
Consensus on Exercise Reporting Template (CERT): Explanation and Elaboration Statement British journal of sports medicine Slade Susan C Dionne Clermont E Underwood Martin Buchbinder Rachelle 5 10 2016
50 23 1428 1437 0306-3674 10.1136/bjsports-2016-096651 10.1136/bjsports-2016-096651
Bernstein’s levels of movement construction: A contemporary perspective Human movement science Profeta Vitor L.S. Turvey Michael T. 2 2018
57 111 133 0167-9457 10.1016/j.humov.2017.11.013 10.1016/j.humov.2017.11.013
A physiotherapist’s perception of their own behavior compared to the perception of their behavior by persons with TBI within the context of telerehabilitation: A self-determination theory perspective Physiotherapy theory and practice O’Neil Jennifer Pelletier Luc Bilodeau Martin Egan Mary Marshall Shawn Sveistrup Heidi 27 2 2022
39 8 1650 1661 0959-3985 10.1080/09593985.2022.2046219 10.1080/09593985.2022.2046219
The majority of patients with Achilles tendinopathy recover fully when treated with exercise alone: a 5-year follow-up The American journal of sports medicine Silbernagel Karin Grävare Brorsson Annelie Lundberg Mari 2011
39 3 607 613 0363-5465 10.1177/0363546510384789 10.1177/0363546510384789 21084657
A comprehensive treatment approach for patellofemoral pain syndrome in young women Physical therapy Thomeé Roland 1 12 1997
77 12 1690 1703 0031-9023 10.1093/ptj/77.12.1690 10.1093/ptj/77.12.1690
Predictors of adherence to home-based physical therapies: a systematic review Disability and rehabilitation Essery Rosie Geraghty Adam W. Kirby Sarah Yardley Lucy 2017
39 6 519 534 0963-8288 10.3109/09638288.2016.1153160 10.3109/09638288.2016.1153160 27097761
Adherence Patterns and Dose Response of Physiotherapy for Rotator Cuff Pathology: Longitudinal Cohort Study JMIR rehabilitation and assistive technologies Burns David Boyer Philip Razmjou Helen Richards Robin Whyne Cari 11 3 2021
8 1 e21374 2369-2529 10.2196/21374 10.2196/21374 33704076
Comparison of three types of exercise in the treatment of rotator cuff tendinopathy/shoulder impingement syndrome: A randomized controlled trial Physiotherapy Heron Stuart R. Woby Steve R. Thompson Dave P. 6 2017
103 2 167 173 0031-9406 10.1016/j.physio.2016.09.001 10.1016/j.physio.2016.09.001 27884499
A self-managed single exercise programme versus usual physiotherapy treatment for rotator cuff tendinopathy: a randomised controlled trial (the SELF study) Clinical rehabilitation Littlewood Chris Bateman Marcus Brown Kim Bury Julie Mawson Sue May Stephen Walters Stephen J 2016
30 7 686 696 0269-2155 10.1177/0269215515593784 10.1177/0269215515593784 26160149
Predicting response to physiotherapy treatment for musculoskeletal shoulder pain: a systematic review BMC musculoskeletal disorders Chester Rachel Shepstone Lee Daniell Helena Sweeting David Lewis Jeremy Jerosch-Herold Christina 8 7 2013
14 1 203 1471-2474 10.1186/1471-2474-14-203 10.1186/1471-2474-14-203 23834747
Comparison of virtual reality exergaming and home exercise programs in patients with subacromial impingement syndrome and scapular dyskinesis: Short term effect Acta Orthopaedica et Traumatologica Turcica Pekyavas Nihan Ozunlu Ergun Nevin 5 2017
51 3 238 242 1017-995X 10.1016/j.aott.2017.03.008 10.1016/j.aott.2017.03.008 28446376
Scapular-focused treatment in patients with shoulder impingement syndrome: a randomized clinical trial Clinical Rheumatology Struyf F. Nijs J. Mollekens S. Jeurissen I. Truijen S. Mottram S. Meeusen R. 2013
32 1 73 85 0770-3198 10.1007/s10067-012-2093-2 10.1007/s10067-012-2093-2 23053685
The Influence of Chronic Pain on Postoperative Pain and Function After Hip Surgery: A Prospective Observational Cohort Study The Journal of Pain Erlenwein Joachim Przemeck Michael Degenhart Astrid Budde Stefan Falla Deborah Quintel Michael Pfingsten Michael Petzke Frank 2 2016
17 2 236 247 1526-5900 10.1016/j.jpain.2015.10.013 10.1016/j.jpain.2015.10.013
Influence of different attentional focus on EMG amplitude and contraction duration during the bench press at different speeds Journal of Sports Sciences Calatayud Joaquin Vinstrup Jonas Jakobsen Markus D. Sundstrup Emil Colado Juan Carlos Andersen Lars L. 2018
36 10 1162 1166 0264-0414 10.1080/02640414.2017.1363403 10.1080/02640414.2017.1363403 28795879
The Effects of Verbal Instructions on Lower Limb Muscles’ Excitation in Back-Squat Research Quarterly for Exercise and Sport Coratella Giuseppe Tornatore Gianpaolo Longo Stefano Borrelli Marta Doria Christian Esposito Fabio Cè Emiliano 2022
93 2 429 435 0270-1367 10.1080/02701367.2020.1840496 10.1080/02701367.2020.1840496 33170116
Speed dependant influence of attentional focusing instructions on force production and muscular activity during isokinetic elbow flexions Human Movement Science Greig Matt Marchant David 2 2014
33 135 148 0167-9457 10.1016/j.humov.2013.08.008 10.1016/j.humov.2013.08.008
External and Internal Focus of Attention Increases Muscular Activation During Bench Press in Resistance-Trained Participants Journal of Strength and Conditioning Research Kristiansen Mathias Samani Afshin Vuillerme Nicolas Madeleine Pascal Hansen Ernst Albin 9 2018
32 9 2442 2451 1064-8011 10.1519/jsc.0000000000002613 10.1519/jsc.0000000000002613 30137029
Thinking about muscles: the neuromuscular effects of attentional focus on accuracy and fatigue Acta Psychologica Lohse Keith R. Sherwood David E. 7 2012
140 3 236 245 0001-6918 10.1016/j.actpsy.2012.05.009 10.1016/j.actpsy.2012.05.009 22683497
Attentional focusing instructions and force production Front Psychol Marchant D.C. 2010
1 210 21833266
