The Acute Effects of a Preload Upper-Body Power Exercise on 50-m Freestyle Performance in Youth Swimmers.

ABSTRACT: Hill, V, Patterson, S, Buckthorpe, M, and Legg, HS. The acute effects of a preload upper-body power exercise on 50-m freestyle performance in youth swimmers. J Strength Cond Res 38(7): 1295-1299, 2024-This study aimed to investigate the acute effects of a medicine ball slam and the optimal recovery time required to induce a postactivation performance enhancement (PAPE) response on 50-meter freestyle swimming performance. Twenty-four (13 female, 11 male) competitive, adolescent swimmers (mean ± SD: age, 16.7 ± 1.2 years; height, 173.3 ± 6.7 cm; mass, 63.1 ± 6.4 kg) participated in a randomized crossover study. After the PAPE intervention (3 × 5 medicine ball slams), subjects had 1-minute, 4-minute, and 8-minute recovery periods before a 50-m maximal freestyle swim. A 1-way repeated-measures ANOVA revealed that different recovery times elicited changes in 50-m performance (F = 12.12, p < 0.0005). After 4 minutes of recovery, 50-m performance was 1.6% (0.47 seconds) faster (95% confidence interval [CI] [0.17-0.77], p < 0.001). When the data were split by sex, after 4 minutes of recovery, 50-m performance was 2% (0.64 seconds) faster for women (95% CI [0.279-0.998], p < 0.001). In conclusion, an upper-body power exercise, before performance, can induce a PAPE response and enhance 50-m freestyle performance after a 4-minute recovery period.

Femoroacetabular Impingement in Ice Hockey Athletes.

ABSTRACT: Femoroacetabular impingement (FAI) in ice hockey is a concern for many athletes. The biomechanics of skating and the injury mechanism, prevalence, identification, and treatment protocols currently available for FAI in ice hockey athletes are important for all coaches and practitioners to understand. This article discusses the underlying anatomical issues and biomechanical considerations surrounding FAI. Furthermore, this article describes the interventions that can be used when encountering FAI and well-established protocols to aid in the return to play. Finally, prevention strategies that can aid in injury prevention are discussed.

Age differences in upper extremity joint moments and strength during a laboratory-based tether-release forward fall arrest in older women.

Age-related declines in upper extremity muscle strength may affect an older adult's ability to land and control a simulated forward fall impact. The role of individual upper extremity joints during a forward fall impact has not been examined. The purpose was to evaluate the age differences in upper extremity joint moment contributions during a simulated forward fall and upper extremity muscle strength in older women. A convenience sample of 68 older women (70 (8) yrs) performed three trials of a simulated forward fall. Percentage joint moments of the upper extremity were recorded. Upper extremity muscle strength was collected via handgrip, hand-held dynamometry of the shoulder and elbow and a custom multi-joint concentric and eccentric strength isokinetic dynamometer protocol. Percentage joint moment contributions differed between women in their sixties and seventies with significantly greater relative shoulder joint involvement (P =.008), coupled with lower elbow joint contributions (P =.004) in comparison to 80 year olds. An increase in each year of age was associated with a 4% increase in elbow contribution (Beta = -0.421, r2 = 17.9, P = 0.0001) and a 3.7% decrease in shoulder contribution (Beta = 0.373, r2 = 14.6, P = 0.002). Older women exhibit different landing strategies as they age. Fall injury prevention research should consider interventions focused on these differences taking into account the contributions of upper extremity strength.

Does functional performance and upper body strength predict upper extremity reaction and movement time in older women?

BACKGROUND: Reaction time to initiate upper limb movement and movement time to place hands on the landing surface may be important factors in forward fall landing and impact, contributing to injury reduction. The aim was to investigate the relationship of physical function and upper body strength to upper limb reaction and movement time in older female participants. METHODS: 75 female participants (72 ± 8 yrs) performed 5 arm response trials. Reaction time (signal to initiation of movement), and movement time (initial movement to contact), were collected using 3D motion capture. Additional variables were: handgrip; sit-to-stand; shoulder flexion and elbow extension strength measured by hand-held dynamometry; one-legged balance; fall risk; and physical activity scores. Prediction variables for reaction and movement time were determined in separate backward selection multiple regression analyses. Significance was set at P < 0.05. FINDINGS: Significant regression equations for RT (r2 = 0.08, P = 0.013) found a relationship between stronger handgrip (Beta = -0.002) and faster reaction time, accounting for 8% variance. For movement time (r2 = 0.06, P = 0.036) greater shoulder flexion strength (Beta = -0.04) was related to faster movement time, explaining 6% variance. Stronger SF strength was related to a decrease in MT by 4%. DISCUSSION: A relationship between arm strength measures and faster upper body reaction and movement time was shown, with 10-20% higher strength associated with a 5% faster response time. Even though this was a relatively weak relationship, given that strength is a modifiable component this provides a potential avenue for future intervention efforts. This in turn could have an impact on forward fall landing and potential reduction of injury risk.

The Effects of a 9-Week Hip Focused Weight Training Program on Hip and Knee Kinematics and Kinetics in Experienced Female Dancers.

Increased involvement of the hip musculature during some movements is associated with enhanced performance and reduced injury risk. However, the impact of hip dominant weight training methods on movement strategy has seen limited attention within the literature. The aim of this study was to evaluate if a 9-week hip dominant weight training intervention promotes a more hip dominant movement strategy leading to an improvement in countermovement jump performance. Twenty-two experienced female dancers were recruited and separated into an intervention (age 24.4 ± 6.3 years, body height 165.5 ± 5.8 cm, body mass 65.9 ± 5.6 kg) and a control (age 22.9 ± 5.6 years, body height 163.3 ± 5.4 cm, body mass 57.4 ± 6.8 kg) group. The intervention group participated in a 9-week hip dominant training intervention, which consisted of a wide stance back squat, Romanian deadlift, hip thrusters, and a bent over row. Hip and knee kinematics and kinetics, and countermovement jump performance were assessed pre and post training. Significant interaction effects were found for peak hip joint moment (p = 0.030, η2 = 0.214) and countermovement jump performance (p = 0.003, η2 = 0.356), indicating an increase in peak hip joint moment and countermovement jump performance for the intervention group. Specifically, the intervention group showed a mean increase in jump height of 11.5%. The data show that the use of a hip dominant weight training strategy can improve hip contribution in the propulsion phase of the countermovement jump. Strength and conditioning specialists should incorporate hip dominant weight training exercises to increase hip strength and improve performance.

The effect of weightlifting shoes on the kinetics and kinematics of the back squat.

Weightlifting shoes (WS) are often used by athletes to facilitate their squat technique; however, the nature of these benefits is not well understood. In this study, the effects of footwear and load on the mechanics of squatting were assessed for 32 participants (age: 25.4 ± 4.4 years; mass 72.87 ± 11.35 kg) grouped by sex and experience. Participants completed loaded and unloaded back squats wearing both WS and athletic shoes (AS). Data were collected utilising a 3D motion capture system synchronised with a force platform and used to calculate kinematic and kinetic descriptors of squatting. For both load conditions, WS gave significantly (P < 0.05) reduced ankle flexion and increased knee flexion than AS, as well as a more upright trunk and greater knee moment for the unloaded condition. In addition, the experienced group experienced a significantly greater increase in knee and hip flexion with WS than the novices when unloaded. These results are consistent with the idea that WS permit a more knee flexed, upright posture during squatting, and provide preliminary evidence that experienced squatters are more able to exploit this effect. Decisions about footwear should recognise the effect of footwear on movement and reflect an athlete's movement capabilities and training objectives.