Sex-Specific Physical Performance Adaptive Responses Are Elicited After 10 Weeks of Load Carriage Conditioning

ABSTRACT Introduction The purpose of this study was to identify and characterize sex-specific physical and psychophysical performance adaptations in response to a novel 10-week training program. Materials and Methods Fifteen males and thirteen females completed a standardized load carriage task (5 km at 5.5 km.h−1, wearing a 23 kg torso-borne vest) before and after 10 weeks of resistance and load carriage training. Psychophysical responses (i.e., heart rate and ratings of perceived exertion) were measured throughout the load carriage task. Physical performance (i.e., countermovement and squat jumps, push-ups, sit-ups, and beep test) was measured at before, mid-way, and after the training program (weeks 0, 6, and 11, respectively). Results Training elicited significant improvements in squat jump maximal force, push-ups, and beep test performance (P < .05). Males outperformed females in all performance measures, with interactions (time, sex) for push-ups, sit-ups, and beep test performance. After training, aerobic capacity improved by 5.4% (42.9 mL· kg−1· min−1 to 45.2 mL· kg−1· min−1) in males but did not improve in females. Psychophysical responses decreased for both sexes (P < .05) during the load carriage task post-training. Conclusion While 10 weeks of standardized training elicited positive adaptations in both physical and psychophysical performance, sex-specific differences were still evident. To lessen these differences, sex-specific training should be considered to optimize load carriage performance.

Body Composition and Power Output In NCAA Division I American Football Linebackers Throughout a Competitive Season

Body composition and power are impactful variables of athletic performance. However, few studies have assessed power and body composition changes from pre-, to mid-, to end-of-season in American Football linebackers. The purpose of this study was to determine how power and body composition respond to a competitive season in Division I Football Championship Series (FCS) American football linebackers. Participants (n=9; Age=19.7 ± 1.5 years; Weight=101.5±11.6 kg; Height=183.3±5.2 cm; [Body Fat percent (BF %) =21.31 ± 6.02%)] performed a Dual-Energy X-ray Absorptiometry (DXA) scan, and power was assessed via three vertical jumps and squat jumps at 40, 60, 80, and 100 kg at three time points: a) 1 week prior to their regular season, b) 2 days after the bye week in the middle of the season, and c) 1 week prior to the completion of the season. An Analysis of Variance (ANOVA) revealed no significant differences (p ≤ 0.05) in power or body composition. These results support past research, indicating power and body composition can be maintained throughout a competitive season. However, more research is needed to determine the optimal programming methods to maintain or improve athletic performance via optimization of body composition and power during a competitive season.

Relationship between General Jump Types and Spike Jump Performance in Elite Female and Male Volleyball Players

In performance testing, it is well-established that general jump types like squat and countermovement jumps have great reliability, but the relationship with volleyball spike jumps is unclear. The objectives of this study were to analyze the relationship between general and spike jumps and to provide improved models for predicting spike jump height by general jump performance. Thirty female and male elite volleyball players performed general and spike jumps in a randomized order. Two AMTI force plates (2000 Hz) and 13 Vicon MX cameras (250 Hz) captured kinematic and kinetic data. Correlation and stepwise-forward regression analyses were conducted at p < 0.05. Simple regression models with general jump height as the only predictor for spike jumps revealed 0.52 ≤ R2 ≤ 0.76 for all general jumps in both sexes (p < 0.05). Alternative models including rate of force development and impulse improved predictions during squat jumps from R2 = 0.76 to R2 = 0.92 (p < 0.05) in females and from R2 = 0.61 to R2 = 0.71 (p < 0.05) in males, and during countermovement jumps with arm swing from R2 = 0.52 to R2 = 0.78 (p < 0.01) in males. The findings include improved prediction models for spike jump height based on general jump performance. The derived formulas can be applied in general jump testing to improve the assessment of sport-specific spike jump performance.

Bilateral deficit: relationships with training history and functional performance

The purpose of the study was to investigate the magnitude of bilateral deficit (BLD) in trained males and examine its relationship with functional performance and recent resistance training history. Ten physically active males (age: 23.02±1.27 years) self-reported the number of unilateral and bilateral exercises within their structured resistance training schedule. During two visits to the laboratory, participants performed unilateral and bilateral squat jumps (SJ) and isometric leg extensions (ILE) for the quantification of BLD. Participants also performed bilateral countermovement jumps (CMJ) and a change of direction (COD) test to quantify functional performance. The performance outcomes and information regarding training history were then correlated with the bilateral index (BLI) metric. The key findings were that: (a) a lower BLD in SJ peak power related to a greater CMJ peak force (r=.728; p=.02) and peak power (r=.750; p=.01), (b) the BLI in the ILE was unrelated to performance outcomes, and (c) BLI was unrelated to the mean number of bilateral and unilateral exercises in the structured resistance training programme of participants. In conclusion, lower levels of BLD may be advantageous for bilateral tests of functional performance (i.e. jumps) however there is a need to consider the mechanical similarity between the performance and BLD measure. Finally, the balance of unilateral and bilateral exercises in an individual’s recent resistance training history is not sensitive to the BLI measured during dynamic or isometric assessments.

The Effect of 8 Weeks of Complex Training Methods on the Countermovement Jump Performance

PURPOSE The purpose of this study was to find out whether a more specific stimulus, such as training which stimulates the production of power above 90% of Pmax (Pmax = maximal average concentric power output), is effective in enhancing the countermovement jump (CMJ) performance using the method of complex pairs or separate execution of the exercises in the complex pair (separate complex pair).METHODSThirty male students of the Faculty of Sports Studies were divided into 2 experimental (EX1, EX2) and 1 control group (CNTR). The experimental groups trained for 8 weeks using the complex training (CT) method twice a week with the same amount of repetitions for each exercise. The complex pair consisted of half-squat jumps with the intensity over 90% of Pmax and plyometric depth-jumps. EX1 trained using the complex pair method with the intracomplex rest interval of up to 15 seconds. EX2 trained all sets of the half-squat jumps first and then all sets of the plyometric exercise. We used non-parametric statistics and linear regression analysis to evaluate the effect on increasing the CMJ performance after the intervention program.RESULTSThere were no significant differences between the pre-test and post-test in any of the experimental groups (p > 0.05), although there were significant differences between the weeks in EX1 and EX2 (p < 0.05). The CMJ performance increased insignificantly (p > 0.05) each week by 0.14 cm in EX1 and by 0.07 cm in EX2. CONCLUSIONThese results did not clearly show the application of the CT methods to be useful in enhancing the CMJ. In practice we recommend using the complex pairs to save training time and increase training intensity. However, an additional longer-term intervention experiment with a bigger sample size and groups randomized by the CMJ parameter (not by Pmax) is needed.

Supramaximal Eccentric Training for Alpine Ski Racing—Strength Training with the Lifter

Eccentric muscular work plays a large role in alpine ski racing. Training with supramaximal eccentric loads (SME) is highly effective to improve eccentric strength but potentially dangerous. Most SME training devices do not allow the athlete to move a barbell freely as they would when performing conventional barbell training. The Intelligent Motion Lifter (IML) allows for safe SME training with a free barbell and no spotters. The IML can be used for free barbell training: a spotter for normal training, eccentric only, concentric only, and squat jumps. It is also a training and testing device for isokinetic and isometric exercise. This commentary addresses the necessity of eccentric training for elite alpine ski racers, the development of the IML and its use in training.