Field Hip Stability Isometric Test (F-HipSIT): Reliability of Assessing the Hip Posterolateral Muscle Strength in Sports Settings.

CONTEXT: The Hip Stability Isometric Test (HipSIT) is commonly employed in clinical settings for evaluating the hip posterolateral muscle strength. In this study, we introduced the "Field Hip Stability Isometric Test" (F-HipSIT) and assessed the intrarater and interrater reliability of this strength assessment specifically designed for sports settings. DESIGN: Reliability study. METHODS: Two independent raters (A and B) went to athletes' training facilities to conduct 2 sessions of F-HipSIT spaced at least 1 week apart. The average peak force value from 3 valid attempts of each leg was recorded and normalized by the participant's body mass for statistical analysis. RESULTS: Thirty male and 30 female amateur athletes took part in this study. Rater A obtained similar values in the first (0.39 [0.05] and 0.44 [0.07] kg·f/kg) and second (0.39 [0.06] and 0.45 [0.07] kg·f/kg) testing days for men and women, respectively. Rater B also found similar values in the first (0.35 [0.06] and 0.42 [0.08] kg·f/kg) and second (0.36 [0.06] and 0.45 [0.08] kg·f/kg) testing days for men and women, respectively. Excellent intrarater intraclass correlation coefficient (ICC) values were found for men (ICC = .922) and women (ICC = .930), with coefficient of variation of 6% to 8% and minimal detectable change of 0.06 to 0.10 kg·f/kg. The F-HipSIT presented good interrater reliability for men (ICC = .857) and women (ICC = .868), with coefficient of variation of 5% and minimal detectable change of 0.05 to 0.06 kg·f/kg. CONCLUSION: The F-HipSIT intrarater and interrater reliability among male and female recreational athletes supports this field test as a quick and convenient screening tool to monitor hip posterolateral muscle strength in sports settings.

Reliability of a Clinical Test for Measuring Eccentric Knee Flexor Strength Using a Handheld Dynamometer.

CONTEXT: Eccentric knee flexor strength assessments have a key role in both prevention and rehabilitation of hamstring strain injuries. OBJECTIVE: To verify the reliability of a clinical test for measuring eccentric knee flexor strength during the Nordic hamstring exercise using a commercially available handheld dynamometer. DESIGN: Reliability study. SETTING: Physical Therapy Laboratory, Federal University of Health Sciences of Porto Alegre (Brazil). PARTICIPANTS: Fifty male amateur athletes (soccer or rugby players; 24 [3] y). MAIN OUTCOME MEASURES: Eccentric knee flexor strength. RESULTS: When compared with a load cell-based device, the clinical test using a handheld dynamometer provided smaller force values (P < .05) with large effect sizes (.92-1.21), moderate intraclass correlation (.60-.62), typical error of 30 to 31 N, and coefficient of variation of 10% to 11%. Regarding the test-retest reproducibility (2 sessions separated by 1 week), the clinical test provided similar force values (P > .05) with only small effect sizes (.20-.27), moderate to good correlation (.67-.76), typical error of 23 to 24 N, and coefficient of variation of 9% to 10%. CONCLUSION: The clinical test with handheld dynamometer proposed by this study can be considered an affordable and relatively reliable tool for eccentric knee flexor strength assessment in the clinical setting, but results should not be directly compared with those provided by load cell-based devices.

Effects of omega-3 supplementation on muscle damage after resistance exercise in young women: a randomized placebo-controlled trial.

BACKGROUND: Omega-3 is a nutritional strategie that have been used to recover muscles from exercise-induced muscle damage in a preventive perspective. AIM: To verify whether omega-3 (ω-3) supplementation after a session of resistance exercise facilitates muscle recovery in women undergoing a balanced diet. METHODS: This clinical trial was registered under the number NCT02839525. Thirty healthy women (22.2 ± 3.3 years) participated in this double-blinded, placebo-controlled trial. They were randomly distributed into ω-3 (n=15) and placebo (n=15) groups. They ingested ω-3 fish oil (3200 mg/day) or placebo (olive oil) at the dinner after the exercise bout (10 sets of 10 unilateral eccentric contractions in a knee extension chair), as well as at lunch for the three subsequent days. In addition, both groups followed a balanced diet along the four days. Muscle soreness and maximal isometric and isokinetic voluntary contractions were assessed immediately before, and 24, 48, and 72 hours after the resistance exercise. MAIN FINDINGS: There was no significant group-time interaction for any outcome. Participants presented increased levels of muscle soreness and reduced muscle strength capacity along the three days after exercise. There was no difference between placebo and ω-3 groups. CONCLUSION: Supplementation of ω-3 fish oil for three days after resistance exercise provided no additional benefits compared to placebo supplementation on recovery of healthy young women following a balanced diet.

Do age and body size affect the eccentric knee flexor strength measured during the Nordic hamstring exercise in male soccer players?

The study aimed to verify how age, height, body mass and body mass index affects the eccentric knee flexor strength during the Nordic hamstring exercise (NHE) in male soccer players. Ten professional soccer clubs were included in this cross-sectional trial. Three hundred and eleven soccer players (192 from senior and 119 from under-20 teams) were assessed using a load-cell based device. Pearson's correlation tests were performed between peak force values (measured in Newtons) and age, height, body mass and body mass index. The individual-limb strength (n = 622 limbs) and the between-limb average strength (n = 322 players) presented no correlation with age (r = 0.12 for both) and height (r = 0.13; r = 0,15), and fair correlations with body mass (r = 0.37; r = 0,41) and body mass index (r = 0.40; r = 0,43). In conclusion, the male soccer players' eccentric knee flexor strength measured during the NHE execution is not affected by age or height. Body mass and body mass index play somewhat effect on strength, thus normalising absolute strength measures by body mass or body mass index can provide more accurate analysis in some contexts.

Eccentric knee flexor strength of professional football players with and without hamstring injury in the prior season.

Both injury history and eccentric knee flexor strength have been associated with risk of football players sustaining hamstring strain injury (HSI). However, it remains unclear whether football players who sustained HSIs in the prior season present persistent eccentric strength deficits. Therefore, the aim of the present study was to verify the eccentric knee flexor strength of professional male football players with and without history of HSI in the prior season. This case-control study assessed 210 professional male football players from 10 Brazilian clubs: 182 included in the control group and 28 in the previously injured group. Players from the injured group had suffered unilateral HSI in the prior season. We measured the knee flexors peak force during the Nordic hamstring exercise and calculated the between-limb asymmetry. Groups were similar for age, body mass and height (p > 0.05). Control group had similar strength values between left and right limbs (376.29 ± 61.77 N vs. 380.28 ± 61.77 N; p = 0.27; d = 0.06), while the previously injured limb was weaker than the contralateral uninjured limb in the injured group (350.87 ± 60.79 N vs. 385.75 ± 63.49 N; p < 0.01; d = 0.56). Thirty-seven percent of players in the control group and 50% in the injured group presented between-limb asymmetry >10%. This study demonstrates that players with history of HSI in the prior season present reduced eccentric knee flexor strength in the injured limb, but half of them have between-limb asymmetry within the most commonly adopted benchmark value of 10%.

Prevalence of Hamstring Strain Injury Risk Factors in Professional and Under-20 Male Football (Soccer) Players.

CONTEXT: Hamstring strain injury (HSI) is the most prevalent injury in football (soccer), and a few intrinsic factors have been associated with higher injury rates. OBJECTIVE: To describe the prevalence of the main intrinsic risk factors for HSI in professional and under-20 football players. DESIGN: Cross-sectional study. SETTING: Physiotherapy laboratory, Federal University of Health Sciences of Porto Alegre (Brazil). PARTICIPANTS: A total of 101 football players (52 professional and 49 under-20 players). INTERVENTION: An evidence-based testing protocol for screening HSI risk factors. MAIN OUTCOME MEASURES: Anamnesis, ultrasonography of the hamstrings, passive straight-leg raise test, Functional Movement Screen, and isokinetic dynamometry were performed. Eleven HSI risk factors for each leg were assessed, besides the player's age as a systemic risk factor. Reports were delivered to the coaching staff. RESULTS: Professionals had greater prevalence of HSI history compared with under-20 players (40% vs 18%). No between-group differences were found for the other screening tests. Altogether, 30% of players had already sustained at least one HSI; 58% had a history of injuries in adjacent regions; 49% had short biceps femoris fascicles; 66% and 21% had poor passive and active flexibility, respectively; 42% and 29% had deficits in functional movements and core stability, respectively; 7% and 26% presented bilateral imbalance for hamstring concentric and eccentric strength, respectively; 87% and 94% obtained low values for hamstring-to-quadriceps conventional and functional ratios, respectively. Two-thirds of players had 3 to 5 risk factors per leg. None of the players was fully free of HSI risk factors. CONCLUSION: Most football players present multiple risk factors for sustaining an HSI. Hamstring weakness is the most prevalent risk factor, but the teams should also be aware of deficits in flexibility, core stability, functional movements, and hamstring fascicle length.