Validity and Test-Retest Reliability of a Novel Push Low-Cost Hand-Held Dynamometer for Knee Strength Assessment during Different Force Ranges

The objective was to assess the instrumental validity and the test–retest reliability of a low-cost hand-held push dynamometer adapted from a load-cell based hanging scale (tHHD) to collect compressive forces in different ranges of compressive forces. Three independent raters applied 50 pre-established compressions each on the tHHD centered on a force platform in three distinct ranges: ~70 N, ~160 N, ~250 N. Knee isometric strength was also assessed on 19 subjects in two sessions (48 h apart) using the tHHD anchored by an inelastic adjustable strap. Knee extension and flexion were assessed with the participant seated on a chair with the feet resting on the floor, knees, and hips flexed at 90°. The isometric force peaks were recorded and compared. The ICC and the Cronbach’s α showed excellent consistency and agreement for both instrumental validity and test–retest reliability (range: 0.89–0.99), as the correlation and determination coefficients (range: 0.80–0.99). The SEM and the MDC analysis returned adequate low values with a coefficient of variation less than 5%. The Bland–Altman results showed consistency and high levels of agreement. The tHHD is a valid method to assess the knee isometric strength, showing portability, cost-effectiveness, and user-friendly interface to provide an effective form to assess the knee isometric strength.

Validity and Test-Retest Reliability of a Novel Push Low-Cost Hand-Held Dynamometer for Knee Strength Assessment During Different Force Ranges

The objective was to assess the instrumental validity and the test-retest reliability of a low-cost hand-held push dynamometer adapted from a load-cell based hanging scale (tHHD) to collect compressive forces in different ranges of compressive forces. Three independent raters applied 50 pre-established compressions each on the tHHD centered on a force platform in 3 distinct ranges: ~70 N, ~160 N, ~250 N. Knee isometric strength was also assessed on 19 subjects in two sessions (48h apart) using the tHHD anchored by an inelastic adjustable strap. Knee extension and flexion were assessed with the participant seated on a chair with the feet resting on the floor, knees, and hips flexed at 90°. The isometric force peaks were recorded and compared. The ICC and the Cronbach’s α showed excellent consistency and agreement for both instrumental validity and test-retest reliability, as the correlation and determination coefficients. The SEM and the MDC analysis returned adequate low values with a coefficient of variation less than 5%. The Bland-Altman results showed consistency and high levels of agreement. The tHHD is a valid method to assess the knee isometric strength, showing portability, cost-effectiveness, and user-friendly interface to provide an effective form to assess the knee isometric strength.

Scapular Dyskinesis in Elite Boxers with Neck Disability and Shoulder Malfunction

Background and Objectives: Neck and shoulder injuries commonly occur during boxing, and scapular dyskinesis is related to those injuries. This study investigated scapular dyskinesis with neck disability and shoulder malfunction in elite boxers. Materials and Methods: Seventy-two elite boxers participated in this study. Scapular dyskinesis was evaluated as normal, subtle, and obvious. Neck disability index (NDI), shoulder internal (IR), and external (ER) range of motion (ROM), isometric strength of IR and ER, and pectoralis minor length were measured and compared with the severity of scapular dyskinesis. Results: Thirty-eight boxers (52.7%) showed scapular dyskinesis. NDI score was significantly different (normal = 3.89 ± 3.08, obvious = 7.36 ± 4.95, p = 0.025). Isometric IR strength was significantly different (normal = 10.48 ± 2.86, obvious = 8.46 ± 1.74, p = 0.01). The length of the pectoralis minor was significantly different (normal = 10.17 ± 0.67, subtle = 9.87 ± 0.79, obvious = 9.47 ± 0.85; p = 0.001), and the dominant and non-dominant arm IR ROM was significantly different (dominant = 57.43 ± 11.98, non-dominant = 64.62 ± 10.3, p = 0.001). Conclusions: The prevalence of scapular dyskinesis is high among elite boxers. Boxers with scapular dyskinesis presented shoulder malfunction as well as neck disability. Further investigation is necessary to examine the relationship between scapular dyskinesis and neck disability in boxers.

Effect of 12 Weeks Core Training on Core Muscle Performance in Rhythmic Gymnastics

Background: Rhythmic gymnastics performance is characterized by technical elements involving flexibility, aerobic capacity and strength. Increased core strength in rhythmic gymnastics could lead to improved sporting performance. Objective: The aim of this study was to analyze the effect of 12 weeks of core muscle training on core muscle performance in rhythmic gymnasts. Methods: A randomized controlled study involving 24 rhythmic gymnastics was conducted. Participants were randomly assigned to a control group (CG; n = 12; age 13.50 ± 3.17 years) or a training group (TG; n = 12; age 14.41 ± 2.35 years). Body composition, isometric strength of trunk, core endurance and core muscle electromyographic activity were measured (EMG) after 12 weeks of core training. Independent sample t-tests were carried out to compare baseline values between groups. A two-way repeated-measures analysis of variance (ANOVA) (time × group) was applied. Results: The TG improved body composition, trunk lean mass (mean differences MD = −0.31; p = 0.040), lean mass (MD = 0.43; p = 0.037) and bone mass (MD = −0.06; p < 0.001) after training. Core training increased isometric strength of trunk, flexion test (MD = −21.53; p = 0.019) and extension test (MD = 22.7; p = 0.049), as well as the prone bridge core endurance test (MD = −11.27; p = 0.040). The EMG values also increased in the TG in prone bridge for front trunk (MD = −58.58; p = 0.026). Conclusions: Core strength training leads to improvements in body composition, as well as improvements in trunk strength and increases in muscle electromyographic activity. These improvements could therefore improve performance during competitive rhythmic gymnastics exercises.

Effects of Dry Needling in Teres Major Muscle in Elite Handball Athletes. A Randomised Controlled Trial

Objective: To determine the effects of dry needling (DN) in active myofascial trigger points in the teres major muscle compared to an untreated control group in pain during throwing actions, shoulder range of motion (ROM), strength, and extensibility of the tissues in professional handball (HB) athletes. Methods: A randomised, single-blinded, controlled clinical trial was designed. Thirty HB athletes with shoulder pain were randomly assigned to the DN group (n = 15) or control group (n = 15). The DN group received a single session of ultrasound-guided DN technique in the teres major muscle. The control group received no intervention. Pain intensity during throwing actions (Numeric Pain Rating Score), shoulder ROM (inclinometer), isometric strength (hand-held dynamometer), and extensibility (inclinometer) were measured before and after treatment. Results: DN group showed statistically significant improvements with large effect sizes for pain intensity (p < 0.001; E.S: 1.3), internal rotation ROM (p < 0.001; E.S: 3.0) and extensibility (p < 0.001; E.S: 2.9) compared to the control group. No statistically significant differences were found for isometric strength (p > 0.05). Conclusion: A single session of DN in the teres major muscle was effective for improving pain intensity during throwing actions, internal rotation ROM and extensibility in HB athletes with shoulder pain.

Physical Fitness Profiling of National Category Table Tennis Players: Implication for Health and Performance

The aims of this study were to: (1) analyze table tennis players’ physical profiles considering and comparing players age categories (i.e., under U12, U14, U16, U20, Senior and Older); and (2) to quantify the correlations among the variables measured by each test. Seventy-one table tennis players (61 men and 10 women, 19.7 ± 11.23 years, 1.65 ± 0.13 m, 59.71 ± 17.72 kg and 21.60 ± 4.22 kg/m2) divided into six age groups, performed a sprint test, forearm isometric strength test, countermovement vertical test, countermovement horizontal test, change of direction ability (CODA) test and flexibility test. U14 players performed better than U12 in all tests (ES = −0.70 to 1.98, moderate to large) except in Sit and Reach (SAR) test (ES = 0.19, trivial). The U16 group also obtained better results than U14 in all tests (ES = 0.77 to −2.31, moderate to large) except for the SAR test (ES = 0.19, trivial). The U20 group performed better than U16 in all the tests (ES = 0.73 to −1.53, moderate to large) except for the 5 m sprint test (ES = −0.02, trivial), 10 m sprint test (ES = −0.51, moderate) and SAR (ES = 0.11, trivial). Differences between Senior and U20 were only found in the arm swing counter movement jump (CMJAS) (ES = −0.82, large) and modified agility test (MAT) (ES = 1.19, large), with the U20 group being better in both variables. The senior group performed better in the MAT test than the older group (ES = 0.94, large). The relation found between forearm isometric strength, vertical jump, horizontal jump, sprint and CODA ability (r = −0.53; ±0.14, 0/0/100, most likely to r = 0.83; ±0.06, 100/0/0, most likely) indicates that these capacities are related in table tennis players. Nevertheless, the lack of association between the sit and reach test with the other capacities may indicate that flexibility is an independent capacity.

Relationship between Biological, Training, and Physical Fitness Variables in the Expression of Performance in Non-Professional Runners

Sports performance is a multifactorial trait that can be associated with individual and environmental characteristics. In this study, the sample comprised 35 male runners, enrolled in the “InTrack” project. Information regarding variables related to runners’ training was obtained via an online questionnaire, while anthropometric and body composition variables, as well as physical fitness components (muscular power, isometric strength, local muscular endurance, agility, and aerobic capacity) were measured, and a global physical fitness score (based on physical fitness components measured) was computed. The Weltman test (3200 m) was used to estimate runners’ pace and their stride frequency. Linear regression was used, taking the running pace as dependent variable. The final model, comprising biological, physical fitness, spatiotemporal, and training variables, explained 86% of the running performance variance. Muscular power (β = −1.02; 95% CI = (−1.69)–(−0.35)), abdominal muscle endurance (β = −4.81; 95% CI = (−7.52)–(−2.10)), isometric strength (β = −422.95; 95% CI = (−689.65)–(−156.25)), global physical fitness (β = 27.14; 95% CI = 9.52–45.03), and stride frequency (β = −2.99; 95% CI = (−4.29)–(−1.69)) were significantly associated with performance, meaning that better results in tests and increasing the stride frequency leads to better performance. Individual characteristics and physical fitness components were demonstrated to be significant predictors for running performance.

The relationship between y balance performance and hip strength in recreationally trained women

This study set one´s sight on the relationship between lower quarter y balance test (YBT-LQ) score with hip isometric strength with recreationally resistance-trained women. Utilizing dynamic balance as a screening tool for lower extremity injury risk has been proposed as a potential solution in injury prevention and injury assessment. A convenience sample of twenty young college females (22.3 ± 2.1 years) with a background in regular strength or plyometric training volunteered to participate in this study. The scores of YBT-LQ for each direction were calculated. A hand-held dynamometer was used to measure the maximum voluntary isometric strength of each participant´s unilateral hip extensors, flexors, adductors, abductors, internal and external rotation muscles. Significant lower normalized score was noted for the dominant limb (81.2 ± 11.7) when compared to non-dominant limb (83.6 ± 12.4) for anterior distance. For the composite score of YBT-LQ, a weak association was noted for hip extension and internal rotation, and moderate association was observed for hip flexion, adduction, and abduction. On the other hand, a strong association was observed between hip external rotators strength (r =0.516). Thus, the main finding of the current study was the strong association observed between hip external rotators strength and composite score of YBT-LQ.