Elastic Resistance and Shoulder Movement Patterns: An Analysis of Reaching Tasks Based on Proprioception

This study departs from the conventional research on horizontal plane reach movements by examining human motor control strategies in vertical plane elastic load reach movements conducted without visual feedback. Here, participants performed shoulder presses with elastic resistances at low, moderate, and high intensities without access to visual information about their hand position, relying exclusively on proprioceptive feedback and synchronizing their movements with a metronome set at a 3 s interval. The results revealed consistent performance symmetry across different intensities in terms of the reach speed (p = 0.254-0.736), return speed (p = 0.205-0.882), and movement distance (p = 0.480-0.919). This discovery underscores the human capacity to uphold bilateral symmetry in movement execution when relying solely on proprioception. Furthermore, this study observed an asymmetric velocity profile where the reach duration remained consistent irrespective of the load (1.15 s), whereas the return duration increased with higher loads (1.39 s-1.45 s). These findings suggest that, in the absence of visual feedback, the asymmetric velocity profile does not result from the execution of the action but rather represents a deliberate deceleration post-reach aimed at achieving the target position as generated by the brain's internal model. These findings hold significant implications for interpreting rehabilitation approaches under settings devoid of visual feedback.

The Effects of Elastic Band Exercises with PNF on Shooting Speed and Accuracy in Ball Hockey Players during the COVID-19 Pandemic

The coronavirus pandemic has affected life and left one of the strongest negative effects on sport. The aim of our study was to evaluate how a simple exercise performed with elastic resistance during the COVID-19 pandemic, when athletes cannot train, affects the basic shooting characteristics of ball hockey players. Extra-league ball hockey players (N = 30, age 19-37 years) were randomly divided into an experimental group, which performed elastic resistance exercises with Proprioceptive Neuromuscular Facilitation (PNF) elements for eight weeks, and a control group, which did not perform any exercises. Before the start of the experiment and after it was completed, the speed and accuracy of shooting were measured. In experimental group, there was no decrease after 8 weeks in the shooting speed, and in the control group, there was a statistically significant decrease. There was a deterioration in the accuracy of shooting in both groups; however, in the experimental group, the deterioration was not significant. The results show that even three simple exercises with elastic resistance according to the PNF concept performed 10 times per day for eight weeks can maintain the level of basic skills of ball hockey players-the speed and accuracy of shooting-even when no other training is performed.

Shoulder and arm muscle activity during elastic band exercises performed in a hospital bed

OBJECTIVE

Muscle atrophy is a common side-effect of bed rest during hospitalization. However, resistance training may minimize or even prevent these complications. Therefore, we evaluated the efficiency of four upper-body elastic resistance exercises that could be performed while lying or sitting in a hospital bed.

METHODS

Twenty-two healthy subjects performed three repetitions of each exercise in a supine and seated position with a perceived intensity of 3 (low) and 8 (high) on the Borg CR10 Scale. Surface electromyography was collected from 12 shoulder and arm muscles (e.g. trapezius, deltoideus, and biceps brachii), and normalized to a maximal voluntary isometric contraction (nEMG).

RESULTS

During all exercises performed at high intensity, moderate (>40%) to high (>60%) levels of nEMG were found for the majority of the analysed muscles, e.g. deltoideus (from 37% to 69%, median 57.5%), trapezius (from 43% to 66%, median 51%), and infraspinatus (from 54% to 66%, median 59%), with the exception of pectoralis major (from 29% to 47%, median 39.5%) and latissimus dorsi (from 15% to 22%, median 18.5%). No significant differences were found between the supine and seated positions for any of the exercises.

CONCLUSION

This study showed that high levels of shoulder and arm muscle activity can be achieved while lying or sitting in a hospital bed using appropriate exercises with elastic bands. The data presented here can be used by physiotherapists as a guideline for selecting suitable and effective strengthening exercises during in-hospital rehabilitation to counteract bed-rest related muscle atrophy in the upper body.

Validity and reliability of elastic resistance bands for measuring shoulder muscle strength

Valid and reliable measurements of muscle strength are important in sport medicine. This study assesses concurrent validity and intrarater reliability (test-retest reliability) of elastic resistance bands for measuring shoulder muscle strength. Altogether, 50 healthy adults [mean age 36.0 (SD: 11.6), 29 women and 21 men] participated in testing and retesting 1-2 weeks later. The maximal elastic resistance (TheraBand) that each participant could hold for 3 s during standing bilateral shoulder abduction to 90° was converted into torque and validated against gold standard maximal voluntary isometric contraction (MVC) (Vishay force transducer) performed unilaterally while lying supine. The intrarater reliability of both tests were high; for the MVC and elastic band test, respectively, ICC(3,1) was 0.98 (95% CI: 0.97-0.99) and 0.99 (95% CI: 0.98-1.00), and measurement error was 4.8% (95% CI: 3.7-5.9) and 4.7% (95% CI: 3.1-6.2). For concurrent validity, ICC(3,1) was 0.96 (95% CI: 0.95-0.98) and measurement error was 8.1% (95% CI: 6.6-9.6), and the elastic band test explained 93% of the variance in the MVC test. However, the elastic band test produced systematically lower torque values than the MVC [56.5 (SD: 26.8) vs 66.5 (SD: 25.5) Nm, P < 0.01]. In conclusion, the test for shoulder muscle strength using elastic resistance bands has excellent validity and reliability, but produces systematically lower torque values than MVC. The reason for the lower torque values may be that the elastic band test has an initial concentric phase and is performed bilaterally and standing upright.

Effectiveness of elastic resistance in rehabilitation of patients with patellofemoral pain syndrome: what is the evidence?

Context:

Patellofemoral pain syndrome (PFPS) is associated with muscle imbalance at the knee and hip. Therapeutic exercise is effective at reducing pain associated with PFPS.

Objective:

To identify and analyze clinical trials of elastic resistance in patients with PFPS to determine its efficacy.

Data Sources:

PubMed, CINAHL, and PEDro databases were searched for terms relevant to PFPS rehabilitation in patients aged 12 to 40 years.

Study Selection:

Only peer-reviewed clinical trials lasting at least 4 weeks and specifying the use of elastic resistance in their protocols were included.

Data Extraction:

Eight eligible studies were analyzed for design, sample, intervention, outcomes, and clinical application.

Results:

The studies included in this review lacked high-quality design, often using exercise as a “quasi-control” condition. Most studies did not provide specific exercise prescription or progression. Although participants in each study reported significant improvements in pain, deficiencies in scientific design limit the conclusion.

Conclusion:

Elastic resistance exercise may reduce pain and improve function and strength in patients with PFPS.

Swiss ball abdominal crunch with added elastic resistance is an effective alternative to training machines

BACKGROUND

Swiss ball training is recommended as a low intensity modality to improve joint position, posture, balance, and neural feedback. However, proper training intensity is difficult to obtain during Swiss ball exercises whereas strengthening exercises on machines usually are performed to induce high level of muscle activation.

PURPOSE

To compare muscle activation as measured by electromyography (EMG) of global core and thigh muscles during abdominal crunches performed on Swiss ball with elastic resistance or on an isotonic training machine when normalized for training intensity.

METHODS

42 untrained individuals (18 men and 24 women) aged 28-67 years participated in the study. EMG activity was measured in 13 muscles during 3 repetitions with a 10 RM load during both abdominal crunches on training ball with elastic resistance and in the same movement utilizing a training machine (seated crunch, Technogym, Cesena, Italy). The order of performance of the exercises was randomized, and EMG amplitude was normalized to maximum voluntary isometric contraction (MVIC) EMG.

RESULTS

When comparing between muscles, normalized EMG was highest in the rectus abdominis (P<0.01) and the external obliques (P<0.01). However, crunches on Swiss ball with elastic resistance showed higher activity of the rectus abdominis than crunches performed on the machine (104±3.8 vs 84±3.8% nEMG respectively, P<0.0001). By contrast, crunches performed on Swiss ball induced lower activity of the rectus femoris than crunches in training machine (27±3.7 vs 65±3.8% nEMG respectively, P<0.0001) Further, gender, age and musculoskeletal pain did not significantly influence the findings.

CONCLUSION

Crunches on a Swiss ball with added elastic resistance induces high rectus abdominis activity accompanied by low hip flexor activity which could be beneficial for individuals with low back pain. In opposition, the lower rectus abdominis activity and higher rectus femoris activity observed in machine warrant caution for individuals with lumbar pain. Importantly, both men and women, younger and elderly, and individuals with and without pain benefitted equally from the exercises.

Electromyographic activity of scapular muscles during diagonal patterns using elastic resistance and free weights

PURPOSE/BACKGROUND

Abnormalities in glenohumeral rhythm and neuromuscular control of the upper trapezius (UT), middle trapezius (MT), lower trapezius (LT) and serratus anterior (SA) muscles have been identified in individuals with shoulder pain. Upper extremity diagonal or proprioceptive neuromuscular facilitation (PNF) patterns have been suggested as effective means of activating scapular muscles, yet few studies have compared muscular activation during diagonal patterns with varying modes of resistance. The purpose of this study is to determine which type of resistance and PNF pattern combination best elicits electromyographic (EMG) activity of the scapular muscles.

METHODS

Twenty one healthy subjects with no history of scapulohumeral dysfunction were recruited from a population of convenience. Surface electrodes were applied to the SA, UT, MT and LT and EMG data collected for each muscle as the subject performed resisted UE D1 flexion, UE D1 extension, UE D2 flexion and UE D2 extension with elastic resistance and a three pound weight.

RESULTS

No significant differences were found between scapular muscle activity during D1 flexion when using elastic resistance and when using a weight. UT, MT and LT values were also not significantly different during D2 flexion when using elastic resistance vs. using a weight. The activity of the SA remained relatively the same during all patterns. The LT activity was significantly greater during D2 flexion with elastic resistance than during the D1 flexion and D1 extension with elastic resistance. MT activity was significantly greater during D2 flexion with elastic resistance as compared to all other patterns except D2 flexion with a weight. UT activity was significantly greater during flexion patterns than extension patterns.

CONCLUSIONS

The upper extremity PNF pattern did significantly affect the mean UT, MT and LT activity but was not found to significantly affect SA activity. The type of resistance did not significantly change muscle activity when used in the same diagonal patterns.