Anterior Cruciate Ligament Reconstructed Female Athletes Exhibit Relative Muscle Dysfunction After Return to Sport

Hand-grip strength in recreational downhill skiers: a comparison to normative reference values

Hand-grip strength was evaluated in 757 recreational downhill skiers and compared to 1021 community-dwellers. Findings are reported for age and sex categories consistent with community-dwelling norms. Effect size (Cohen's d) was calculated to estimate the clinical relevance of strength differences between populations. Most male and half of the female age categories of downhill skiers demonstrated higher grip strength of the dominant hand (moderate to large effect size) compared to the reference population. Hand-grip strength in skiers declined with age at a similar rate as in the reference population. Relative grip strength (per kg body mass) was significantly and positively correlated with physical activity (hours/week), and with the number of ski days per year, and negatively with body mass. Thus, hand-grip strength may be related to the type, volume and intensity of exercise regularly performed. These results can help to assess whether the individual hand-grip strength is above or below average with regard to the normal population and the skier population as well and will support advice for training and/or rehabilitation.

Evaluation of raw segmental bioelectrical impedance variables throughout anterior cruciate ligament reconstruction rehabilitation

Background.Raw bioelectrical impedance analysis (BIA) variables are related to physical function in healthy and diseased populations. Therefore, BIA may be an insightful, noninvasive method of assessment to track following anterior cruciate ligament reconstruction (ACLR).Objectives.Evaluate phase angle, reactance and impedance at 50 kHz (PhA₅₀, Xc₅₀, andZ₅₀, respectively) in the operative (OP) and non-operative (NOP) limbs during ACLR rehabilitation.Approach.Seventeen patient (12 M, 5 F; 18.8 ± 4.8 years) clinic reports were evaluated prior to ACLR (PRE), two- (2 W), six- (6 W), and twelve-weeks (12 W) post-ACLR and at return to sport testing (RTS).Setting.All observations occurred during the participant's physical therapy visits.Measurements.A multi-frequency BIA device measured segmental PhA, Xc, andZ. Linear mixed effects models were used to assess any leg and time interaction and changes over leg and time, independently. Any interactions or main effects were considered significant atp< 0.05.Main results.Significant legxtime interactions were observed for each variable. PhA₅₀and Xc₅₀of NOP were higher (p< 0.001) than OP at each time point by an average of by 0.9° and 4.9 Ω, respectively. In OP, PhA₅₀and Xc₅₀decreased from PRE to 2 W and increased from 6 to 12 W and 12 W to RTS (p< 0.01, for all). At RTS, PhA₅₀and Xc₅₀were similar to PRE in OP (p> 0.05). ForZ₅₀, the OP leg did not change over time (p> 0.05).Z₅₀was greater in NOP at 2 and 6 W (p< 0.01, for both). There were differences in PhA₅₀in NOP between PRE and 6 W and from 6 W to RTS (p< 0.05 for both). Xc₅₀did not change (p> 0.05), andZ₅₀PRE was lower than at 2 W (p< 0.05).Significance.A multi-frequency BIA device can detect changes in segmental BIA variables following ACLR.

New Frontiers of Body Composition in Sport

The body composition phenotype of an athlete displays the complex interaction among genotype, physiological and metabolic demands of a sport, diet, and physical training. Observational studies dominate the literature and describe the sport-specific physique characteristics (size, shape, and composition) of adult athletes by gender and levels of competition. Limited data reveal how body composition measurements can benefit an athlete. Thus, the objective is to identify purposeful measurements of body composition, notably fat and lean muscle masses, and determine their impact on the health and performance of athletes. Areas of interest include relationships among total and regional body composition measurements, muscle function, sport-specific performance, risk of injury, return to sport after injury, and identification of activity-induced fluid shifts. Discussion includes the application of specific uses of dual X-ray absorptiometry and bioelectrical impedance including an emphasis on the need to minimize measurement errors and standardize protocols, and highlights opportunities for future research. This focus on functional body composition can benefit the health and optimize the performance of an athlete.