Journal of Strength and Conditioning Research最新文献

Abstract: Brooks, SG, Peach, HD, Howden, R, Lowrie, J, and Marino, JS. Impact of perfectionism on the risk of the female athlete triad in collegiate athletes. J Strength Cond Res XX(X): 000-000, 2024-The female athlete triad is a metabolic syndrome affecting physically active female athletes, especially in high-level athletics. Little is known about the relationship between psychological factors and triad risk. This study aimed to investigate the risk of triad development and the relationship with perfectionistic tendencies in female collegiate athletes. Division I female college athletes (N = 25) (mean age 20.2 ± 1.2) completed the Sport Multidimensional Perfectionism Scale 2, Low Energy Availability in Females Questionnaire, Female Athlete Screening Tool, and medical history surveys. Subjects then received a whole-body dual-energy x-ray absorptiometry scan for body composition and bone density measurements; 60% of subjects were at a moderate risk of developing the triad and 8% were at a high risk. This indicates that there is a high prevalence of triad risk in this population, pointing to the need for better screenings. Subjects with greater perfectionistic tendencies had a greater risk for triad development (r = 0.58), especially when those tendencies manifest in maladaptive dimensions (concerns over mistakes r = 0.75, doubts about actions r = 0.64) (p ≤ 0.05). No significant correlations were established between adaptive dimensions and triad risk, suggesting that athletes with high perfectionistic tendencies that manifest in positive ways may not experience increased risk of the triad or disordered eating. The findings provide a greater understanding of the psychological role perfectionism plays in the development of the triad and help identify behaviors that place athletes at a higher risk.

Abstract: Horníková, H, Hadža, R, and Zemková, E. The contribution of perceptual-cognitive skills to reactive agility in early and middle adolescent soccer players. J Strength Cond Res XX(X): 000-000, 2024-Agility performance increased from childhood to mid-adolescence, followed by a plateau until early adulthood. Because adolescence is crucial for the development of perceptual-cognitive skills, the question is whether and to what extent its contribution to reactive agility increases during developmental periods of adolescence in invasive sports athletes. This study investigated the association of reactive agility with the speed of decision making, sprint speed, and explosive strength in early and middle adolescent soccer players. They performed reactive and preplanned Y-shaped agility tests, choice reaction time test, modified half T-test, 30-m sprint (10 m split), and countermovement jump (CMJ). The reactive agility time in both age groups significantly correlated with 30-m sprint time (r = 0.839, p < 0.001, and r = 0.745, p = 0.001, respectively), pre-planned Y-shaped agility time (r = 0.828, p < 0.001, and r = 0.644, p = 0.007, respectively), 10-m sprint time (r = 0.823, p < 0.001, and r = 0.775, p < 0.001, respectively), time in modified half T-test (r = 0.723, p < 0.001, and r = 0.630, p = 0.009, respectively), and CMJ height (r = -0.744, p < 0.001, and r = -0.615, p = 0.013, respectively), although with the index of reactivity in middle adolescent soccer players only (r = 0.615, p = 0.011). Based on R2, the explained proportion of variance was 53.6% for linear sprint speed and 30.1% for a change of direction speed in early adolescence, whereas it was 54.6% for acceleration speed and 31.8% for decision-making in middle adolescence. This indicates the significant contribution of speed factors to reactive agility in both adolescent groups, whereas perceptual-cognitive factors in middle adolescent soccer players only. It seems that even during the relatively short period of adolescence, the changes occur in the contribution of perceptual-cognitive skills to reactive agility in athletes practising invasive sports.

Abstract: Hogge, R, Mascheri, M, Shurik, D, Hanney, WJ, and Anderson, AW. High-fatigue dynamic resistance exercise induces significant hypoalgesia effect. J Strength Cond Res XX(X): 000-000, 2024-Although dynamic resistance exercise is a recommended treatment for patients with musculoskeletal pain, optimal intensity to create hypoalgesia has not been established. Response to exercise may also be affected by biopsychosocial factors that modulate pain response. The first purpose was to compare the immediate effects of a high-fatigue/exertion leg extension, low-fatigue/exertion leg extension, and control condition on pressure pain threshold (PPT) applied to the quadriceps (local effects) and trapezius (systemic effects). The second purpose was to examine if psychological and pain sensitivity factors affected response to exercise. As a within-subject design, subjects completed psychological questionnaires, a control condition, and a 1-repetition maximum (1RM) during the first session. Subjects attended 2 more sessions where they completed 3 sets of a leg extension exercise at 50% of their 1RM until they reached a fatigue level of high fatigue (8/10 on the Borg CR-10) or low fatigue (3/10) with a randomized session order. A within-subject repeated-measures ANOVA was conducted (significance set at p < 0.05). High-fatigue exercise produced significantly higher PPT at the quadriceps than quiet rest after each set (F[6,162] = 3.25, p < 0.01, partial eta2 = 0.11). During low-fatigue exercise, individuals with an efficient endogenous pain inhibitory capacity displayed significantly higher PPT at the trapezius (F[2.14, 55.61] = 3.31, p = 0.03, partial eta2 = 0.11). Lower fear of pain was moderately associated with greater PPT increases at the trapezius (r = -0.38, p = 0.04). Although high-fatigue exercise produces immediate local hypoalgesia, systemic hypoalgesia is affected by variability in pain inhibition and fear of pain.

Abstract: O' Connor, C, Mc Intyre, M, Delahunt, E, and Thorborg, K. Maximum isometric hip adduction squeeze and abduction press strength values in men's rugby union players at select timepoints throughout a competitive season. J Strength Cond Res XX(X): 000-000, 2024-The purpose of this research was to report hip adduction and abduction strength values in men's rugby union players at select timepoints throughout a competitive season and to examine if differences exist between time of season and hip-testing positions. This cross-sectional repeated measures study design consisted of 15 male rugby union players competing at senior club level. Maximum isometric hip adduction and abduction strength were measured using a ForceFrame in 3 testing positions at specific timepoints: start of preseason (T1), start of competitive season (T2), mid-season period 1 (T3), and mid-season period 2 (T4). At group level, hip adduction strength (N·kg-1) increased from T1 to T2 in all testing positions, with significant increases observed in the 0° hip-flexion short-lever position (p = 0.048), and 45° hip-flexion position (p = 0.032). No significant changes occurred in hip abduction strength (N·kg-1). Hip adduction:abduction strength ratio increased from T1 to T2, with a significant increase observed in the 0° hip-flexion short-lever position (p = 0.008). At individual level, large variations from baseline strength (N·kg-1) were observed between timepoints for hip adduction strength, abduction strength, and adduction:abduction strength ratio. In conclusion, the present study shows increases in hip adduction strength and hip adduction:abduction strength ratio from the start of preseason to the beginning of the competitive season, with no other significant changes in hip strength observed throughout the season. Individual and frequent hip strength monitoring throughout the season and a more individualized exercise prescription approach may be needed for rugby union players, in addition to a more generalized focus on improving adductor and abductor strength.

Abstract: Van Roie, E, van Uffelen, J, and Delecluse, C. Stair-climbing versus machine-based resistance exercise to improve muscle power among older adults: a non-inferiority trial. J Strength Cond Res XX(X): 000-000, 2024-Machine-based resistance training (RT) can reduce the age-related loss in muscle power (Pmax). However, weight-bearing exercises have greater potential for implementation. This study investigated whether stair-climbing exercise (STAIR) was non-inferior to improve Pmax compared with machine-based RT among older adults. Functional capacity tests were secondary outcomes. Older adults (30♂ and 16♀; 70.9 ± 4.3 years) were randomly assigned to RT or STAIR (n = 23 per group). Supervised laboratory-based training sessions were performed 2 times per week for 12 weeks. In week 1-4, exercises were performed at controlled speed (hypertrophy-oriented; 4 × 12-15 repetitions; 55% of 1 repetition maximum (1RM) in RT; step-up exercise with height of 30-40 cm in STAIR), in week 5-12 as fast as possible (power-oriented, 4 × 12 repetitions; 40% of 1RM for RT and 4 × 2 flights of 6 steps for STAIR). Leg-extensor Pmax and functional capacity were measured pre-intervention and post-intervention, and Pmax also after 4 weeks of training. Gains in Pmax were not statistically different in RT (19.5 ± 12.2%) and STAIR (13.7 ± 16.5%) (d = 0.39, pint = 0.086), whereas non-inferiority analyses were inconclusive (between-group difference in gains: 5.8% (95% CI -3.1 to 14.6); non-inferiority limit 3.9%). STAIR increased more in stair ascent performance (d = 0.45-0.61, pint < 0.05) than RT. STAIR and RT improved similarly on 10-m fast walk, 5-repetition sit-to-stand, and countermovement jump (pint > 0.05). To conclude, STAIR and RT both induced significant changes in Pmax and functional capacity in older adults. STAIR was beneficial over RT for gains in stair-climbing performance. Future research should investigate the effects of STAIR in a home-based unsupervised setting.

Abstract: De Bleecker, C, Vermeulen, S, Willems, T, Segers, V, Spanhove, V, Leys, R, Vanrenterghem, J, and De Ridder, R. Validation of impact forces estimated by wearable device VERT in volleyball validation impact forces VERT. J Strength Cond Res XX(X): 000-000, 2024-As volleyball players are exposed to high volumes of forceful jump-landing actions, the risk of injuries is increased. Wearable technology such as the VERT device offers a promising avenue for load monitoring of volleyball players, potentially allowing better control of intensity of training and matches to minimize the likelihood of injuries. Although validity of jump counts and jump height is well investigated, studies validating impact forces estimated by VERT device referenced to force plate data are scarce. The objective of this study was to validate the use of VERT for the estimation of impact forces during volleyball. Twenty-one volleyball players of different levels performed countermovement jumps (CMJ), block jumps, spike jumps, and a set with a combination of several volleyball jump-landing tasks. Impact forces estimated by VERT were compared with resultant force values measured using a force plate. A total of 221 spike jumps, 286 block jumps, and 203 CMJ were analyzed. Given the identified proportional bias and heteroscedasticity, an adapted Bland-Altman plot featuring the line of best fit and V-shaped 95% confidence intervals instead of classic limits of agreement was created. Furthermore, our results suggest a proportional bias between the 2 measurements, with the VERT sensor tending to overestimate impact forces compared with the force plate, increasingly at higher mean values. Therefore, the VERT algorithm has not been proven valid for quantifying impact forces. However, a correction factor is proposed to obtain better results for impact forces estimated by VERT, making it suitable for implementation in sport contexts.

Abstract: Polletta, J, Leung, K, Diaz, D, Branum, N, and Mokha, M. Influence of interlimb lean muscle mass asymmetry on countermovement jump neuromuscular performance qualities among American football players. J Strength Cond Res XX(X): 000-000, 2024-Body composition is a determinant of athletic performance. The purpose of this study was to determine the influence of lower limb lean muscle mass (LMM) asymmetry on countermovement jump (CMJ) performance and kinetic asymmetry during both eccentric and concentric CMJ phases. Seventy-four American football players (age, 23.0 ± 0.9 years; height, 1.86 ± 0.07 m; mass, 104.9 ± 21.6 kg; lean body mass, 88.7 ± 12.5 kg) training for the 2024 National Football League draft underwent body composition assessment using an InBody 270 bioelectrical impedance analyzer that yielded right and left leg LMM in kg. Subjects then performed 3 CMJs on dual uniaxial force plates that allowed for the calculation of jump height (JH), reactive strength index modified (RSImod), and interlimb percentage asymmetry of peak force and impulse for eccentric and concentric phases. A paired t-test and Pearson Product-moment Correlation Coefficients calculated the difference between left and right LMM and the associations between the symmetry variables, respectively, p ≤ 0.05. Right and left leg LMM were significantly different (t(73) = 3.772, p ≤ 0.001). However, no significant relationships were found between lower limb LMM asymmetry (0.67 ± 0.67%) and any asymmetry in CMJ eccentric peak force (4.77 ± 3.75%), r(72) = 0.001, p = 0.954; eccentric deceleration impulse (5.23 ± 4.36%), r(72) = 0.158, p = 0.180; concentric peak force (2.99 ± 2.54%), r(72) = -0.70, p = 0.553; concentric impulse (3.06 ± 2.97%), r(72) = 111, p = 0.347; JH (41.8 ± 7.3 cm), r(72) = -0.205, p = 0.08; or RSImod (0.53 ± 0.14 m·s-1), r(72) = -0.151, p = 0.199. The magnitude of LMM asymmetry did not influence CMJ performance or asymmetry magnitude. Reducing CMJ kinetic asymmetry may require targeted programming, especially for the eccentric loading phase.

Abstract: García-Sánchez, C, Jiménez-Ormeño, E, Lominchar-Ramos, JM, Giráldez-Costas, V, McMahon, JJ, and Soriano, MA. Effects of a short-term detraining period on neuromuscular performance in female handball players. J Strength Cond Res XX(X): 000-000, 2024-The aim of this study was to determine the effects of a 3-week detraining period on lower limbs' neuromuscular performance in female handball players. Fourteen semi-professional players (age: 20.50 ± 2.98 years; height: 1.67 ± 0.06 m; body mass: 66.89 ± 8.75 kg) were evaluated using force plates on 3 separate occasions to assess the maximum and rapid force production by the isometric mid-thigh pull (IMTP) and the ballistic capabilities by countermovement jump (CMJ). The intraclass correlation coefficient, coefficient of variation, standard error of the measurement, and smallest detectable difference were calculated using the first 2 testing sessions. Pre- and postdetraining differences were calculated comparing the first and third testing sessions, using paired t-tests or Wilcoxon test when appropriate and Hedges g effect sizes (ES). The level of significance was set at ρ ≤ 0.05. There were no significant or meaningful differences in maximum and rapid force production capabilities assessed during the IMTP (p > 0.05). However, there was a significant detriment with small ES in CMJ jump height, modified reactive strength index, peak and mean propulsive force, peak and mean braking force, and braking phase duration (p < 0.05). These findings suggest that although maximum and rapid force production capabilities were not altered among female handball players after a 3-week detraining period, their ballistic capabilities decreased, especially those affecting the eccentric part of a fast dynamic task. They also highlight the importance of testing, planning, and programming in response to the fluctuations in handball players' physical performance over the season.

Abstract: Magee, MK, Fields, JB, Jagim, A, Lockard, B, Miller, A, Stroiney, D, and Jones, MT. Estimation of whole-body bone mineral density through air displacement plethysmography in a large sample of elite athletes. J Strength Cond Res XX(X): 000-000, 2024-Dual-energy x-ray absorptiometry (DXA) is used to determine bone mineral density (BMD) and body composition. Regulations and cost may limit DXA's utility in some athletic settings. Air displacement plethysmography (ADP), while able to measure body composition, does not measure BMD. The purpose was to evaluate the influence of body composition parameters obtained from ADP on BMD. Collegiate athletes (males, n = 153; females, n = 208) underwent ADP and DXA assessments. For ADP testing, the Brozek equation was used to estimate body fat percent (BF%) and fat-free mass (FFM) from body density. Dual-energy x-ray absorptiometry tests were completed to obtain BMD using the whole-body scan mode. Stepwise regression was conducted using age, body mass, height, sex, race, FFM (ADP), BF% (ADP), and sport type as independent variables. Total BMD (DXA) was the dependent variable. Accuracy and precision of the final equation were evaluated through Bland-Altman and linear regression. The final regression equation yielded an R2 of 0.691 with race, mass, BF%, age, and sport type as significant predictors (p < 0.05) of BMD. Bland-Altman and linear regression showed systematic {95% confidence interval [CI] (-0.619 to -0.360)} and proportional bias (95% CI [0.173-0.374]). Although an ADP-derived regression equation may not provide a precise prediction of BMD, it may be useful to establish risk for low BMD if DXA is unavailable. Dual-energy x-ray absorptiometry may not be feasible for some athletic programs; therefore, an estimation equation for BMD derived from ADP values is advantageous for practitioners. This equation may assist in screening athletes for risk of low BMD.

Abstract: Mitchinson, CJ, Best, S, Caruso, J, and Bollinger, LM. Cardiorespiratory responses to flywheel-based inertial training squats with varying moments of inertia. J Strength Cond Res XX(X): 000-000, 2024-Flywheel-based inertial training (FIT) has gained popularity as a means to enhance muscle hypertrophy. Other applications, such as aerobic exercise training, remain unexplored. The aim of this study was to determine the cardiorespiratory responses to acute FIT with varying moments of inertia (MOIs). Methods: Overall, 20 (10 M, 10 F) healthy, physically active subjects underwent maximal graded exercise testing and completed 3 bouts of FIT exercise (1 familiarization session and 2 identical data collection sessions). Subjects completed quarter squats (60° peak knee flexion) at a pace of 50 squats·minute-1 until volitional fatigue. Flywheel-based inertial training MOI was increased by 0.005 kg·m2 every 3 minutes until a final workload of 0.020 kg·m2. Heart rate and gas exchange data were collected continuously and averaged over the final 60 s of each stage. Data were analyzed by a linear mixed model. Results: During the final testing session, there was a main effect of MOI to increase heart rate (HR), V̇o2, and RER. Men displayed greater oxygen consumption, but a similar %V̇o2peak compared with women. We noted a significant inertia × sex interaction where RER tended to be lesser in women at higher MOI. In the final stage of exercise (MOI: 0.020 kg·m2), HR and V̇o2 were approximately 75-80 and 55% of peak, respectively, and RER was approximately 0.95-1.00. Conclusions: FIT quarter squats elicit moderate HR and V̇o2 responses, but near-maximal RER suggests a novel metabolic training stimulus. This exercise may supersede the lactate threshold and may not be sustainable for prolonged times. The physiological and performance effects of training in this manner are unclear.