Lower-body Power Research Articles

Behavioral Modification Enhances the Benefits from Structured Aerobic and Resistance Training.

Behavioral modification (BM) is a strategy designed to sustain or restore well-being through effects such as enhanced relaxation, reduced stress, and improved sleep. Few studies have explored the role of BM delivered in the context of fitness programs for healthy adults. Thus, the purpose of this investigation was to examine whether BM combined with aerobic and resistance training programs would improve health and fitness measures more than the exercise training alone. Thirty-two healthy fitness club members (19 men) were randomized to receive a BM program (n=15) or an equal-attention (EA) control (n=17). BM consisted of twelve, 10-min education sessions between a trained fitness professional and the participant, coupled with weekly, individualized relaxation, stress reduction, and sleep improvement assignments. All participants engaged in 1 h of coached resistance training and remotely guided aerobic exercise thrice weekly for 12 weeks. Fitness measures (aerobic performance, body composition, muscle strength and endurance, lower-body power), sleep characteristics, and heart rate variability (HRV) were obtained at baseline and after the 12-week program. BM resulted in greater improvements in aerobic performance (increased maximum oxygen uptake, metabolic (lactate) threshold, and percent of maximum oxygen uptake at which metabolic threshold occurred), peak and average lower-body power, and body composition (decreased body fat percentage and fat mass) compared to EA. BM also positively influenced parasympathetic tone through increased High-frequency HRV. BM resulted in greater improvements in fitness measures, body composition, and heart rate variability compared with EA. These findings have intriguing implications regarding the role of BM in augmenting health and physical performance.

Changes in Muscle Power and Muscle Morphology with Different Volumes of Fast Eccentric Half-Squats.

The aim of the study was to evaluate power performance and muscle morphology adaptations in response to 5 weeks of fast-eccentric squat training (FEST) performed twice per week, with three different training volumes. Twenty-five moderately trained females were assigned into three groups performing eight repetitions of FEST of either four sets (4 × 8 group; N = 9), 6 sets (6 × 8 group; N = 8) or eight sets (8 × 8 group, N = 8). Before and after the intervention, countermovement jumping height (CMJh) and power (CMJp), half squat maximal strength (1-RM), quadriceps cross-sectional area (QCSA) and vastus lateralis (VL) architecture and fiber type composition were evaluated. Significant increases (p < 0.05) were found for all groups, with no differences among them in 1-RM (4 × 8: 14.8 ± 8.2%, 6 × 8: 13.1 ± 9.2% and 8 × 8: 21.6 ± 7.0%), CMJh (4 × 8: 12.5 ± 8.5%, 6 × 8: 11.3 ± 9.3% and 8 × 8: 7.0 ± 6.2%), CMJp (4 × 8: 9.1 ± 6.0%, 6 × 8: 7.1 ± 5.2% and 8 × 8: 5.0 ± 3.9%) and QCSA (4 × 8: 7.7 ± 4.7%, 6 × 8: 9.0 ± 6.8% and 8 × 8: 8.2 ± 6.5%). Muscle fiber type distribution remained unaltered after training in all groups. VL fascicle length increased and fascicle angle decreased only in 6 × 8 and 8 × 8 groups. In conclusion, four sets of eight fast-eccentric squats/week increase lower body power and strength performance and maintain type IIX muscle fibers after 5 weeks, at least in moderately trained females.

The Effects of a Multi-Ingredient Performance Supplement Combined with Resistance Training on Exercise Volume, Muscular Strength, and Body Composition.

The effects of a multi-ingredient performance supplement (MIPS) incorporating a mixture of branched chain amino acids, beta-alanine, glutamine, creatine, and piperine on resistance training (RT)-induced adaptations remains unclear. Therefore, the purpose of this study was to investigate the effects of this investigational MIPS during six weeks of RT on performance and body composition. Thirty recreationally trained males and females were recruited for this pair-matched, double-blind, placebo-controlled investigation. Subjects were assigned to consume either an experimental MIPS (MIPS) (n = 15) or a placebo (PLA) (n = 15) concurrently with a six-week periodized RT program. Body composition, one-repetition maximum (1RM), and muscular power were assessed at pre- and post-training. Weekly relative volume load was compared between groups. The MIPS and PLA groups demonstrated a significant increase in total body mass (MIPS = +2.9 ± 1.3%; PLA = +2.5 ± 1.7%) and lean mass (MIPS = +5.0 ± 2.1%; PLA = +3.1 ± 1.9%) (p < 0.001) with no changes in fat mass. There were no group × time interactions for any of the body composition measures. Both groups demonstrated similar improvements in maximum strength for the back squat, bench press, and deadlift as well as lower body power from pre- to post-training (p < 0.001). Within the limitations of the current investigation, results failed to demonstrate the benefits of the experimental MIPS for muscular strength and body composition across six weeks of RT compared to PLA.

Multidomain Geriatric Screen and Physical Fitness Assessment Identify Prefrailty/Frailty and Potentially Modifiable Risk Factors in Community-Dwelling Older Adults

Frailty begins in middle life and manifests as a decline in functional fitness. We described a model for community frailty screening and factors associated with prefrailty and frailty and fitness measures to distinguish prefrail/frail from robust older adults. We also compared the Fatigue, Resistance, Ambulation, Illnesses and Loss of weight (FRAIL) scale against Fried frailty phenotype and Frailty Index (FI). Community-dwelling adults ≥55 years old were designated robust, prefrail or frail using FRAIL. The multidomain geriatric screen included social profiling and cognitive, psychological and nutritional assessments. Physical fitness assessments included flexibility, grip strength, upper limb dexterity, lower body strength and power, tandem and dynamic balance and cardiorespiratory endurance. In 135 subjects, 99 (73.3%) were robust, 34 (25.2%) were prefrail and 2 (1.5%) were frail. After adjusting for age and sex, depression (odds ratio [OR], 2.90; 95% confidence interval [CI], 1.05-7.90; P = 0.040) and malnutrition (OR, 6.07; 95% CI, 2.52-14.64; P <0.001) were independently associated with prefrailty/frailty. Prefrail/frail participants had significantly poorer performance in upper limb dexterity (P = 0.030), lower limb power (P = 0.003), tandem and dynamic balance (P = 0.031) and endurance (P = 0.006). Except for balance and flexibility, all fitness measures differentiated prefrail/frail from robust women. In men, only lower body strength was significantly associated with frailty. Area under receiver operating characteristic curves for FRAIL against FI and Fried were 0.808 (0.688-0.927, P <0.001) and 0.645 (0.546-0.744, P = 0.005), respectively. Mood and nutrition are targets in frailty prevention. Physical fitness declines early in frailty and manifests differentially in both genders.

Systematic Review of the Association Between Physical Fitness and Musculoskeletal Injury Risk: Part 3-Flexibility, Power, Speed, Balance, and Agility.

de la Motte, SJ, Lisman, P, Gribbin, TC, Murphy, K, and Deuster, PA. Systematic review of the association between physical fitness and musculoskeletal injury risk: part 3-flexibility, power, speed, balance, and agility. J Strength Cond Res 33(6): 1723-1735, 2019-We performed a systematic review and evaluation of the existing scientific literature on the association between flexibility, power, speed, balance, and agility, and musculoskeletal injury (MSK-I) risk in military and civilian populations. MEDLINE, EBSCO, EMBASE, and the Defense Technical Information Center were searched for original studies published from 1970 to 2015 that examined associations between these physical fitness measures (flexibility, power, speed, balance, and agility) and MSK-I. Methodological quality and strength of the evidence were determined after criteria adapted from previously published systematic reviews. Twenty-seven of 4,229 citations met our inclusion criteria. Primary findings indicate that there is (a) moderate evidence that hamstring flexibility, as measured by performance on a sit-and-reach test or active straight leg raise test assessed with goniometry, and ankle flexibility, assessed with goniometry, are associated with MSK-I risk; (b) moderate evidence that lower body power, as measured by performance on a standing broad jump or vertical jump with no countermovement, is associated with MSK-I risk; (c) moderate evidence that slow sprint speed is associated with MSK-I risk; (d) moderate evidence that poor performance on a single-leg balance test is associated with increased risk for ankle sprain; and (e) insufficient evidence that agility is associated with MSK-I risk. Several measures of flexibility, power, speed, and balance are risk factors for training-related MSK-I in military and civilian athletic populations. Importantly, these findings can be useful for military, first responder, and athletic communities who are seeking evidence-based metrics for assessing or stratifying populations for risk of MSK-I.

Associations between Fitness Measures and Change of Direction Speeds with and without Occupational Loads in Female Police Officers.

Female police officers may be required to pursue offenders on foot while wearing occupational loads. The aim of this study was to determine relationships between fitness measures and change of direction speed (CODS) in female police officers and the influence of their occupational loads. Retrospective data were provided for 27 female police officers (age = 32.19 ± 5.09 y, height = 162.78 ± 5.01 cm, and mass = 71.31 ± 13.42 kg) and included fitness measures of: lower-body power (standing long jump (SLJ)), upper-body and trunk muscle endurance (push-up (PU) and sit-up (SU)), aerobic power (estimated VO2max), and CODS (Illinois agility test). The CODS test was performed without and with occupational load (10 kg). Paired sample t-tests (between-load conditions) and Pearson’s correlations (relationships between measures) were performed with linear regression analysis used to account for the contribution of measures to unloaded and loaded CODS performance. CODS was significantly slower when loaded (unloaded = ~23.17 s, loaded = ~24.14 s, p < 0.001) with a strong, significant relationship between load conditions (r = 0.956, p < 0.001). Moderate to strong, significant relationships were found between all fitness measures ranging from estimated VO2max (r = −0.448) to SU (r = −0.673) in the unloaded condition, with the strength of these relationships increasing in the loaded condition accounting for 61% to 67% of the variance, respectively. While unloaded agility test performance was strongly associated with loaded performance, female police officer CODS was significantly reduced when carrying occupational loads. A variety of fitness measures that influence officer CODS performances become increasingly important when occupational loads are carried.

Sex Differences in Muscle-Bone Interactions in Chinese Men and Women

Muscle-bone interactions are important for bone health as mechanical forces from muscular contraction place large stresses on bone. Little is known about sex differences in bone and muscle characteristics in Asians. PURPOSE: To examine sex differences in bone characteristics, grip strength, and lower body strength and power in Chinese adults (n=53). METHODS: Chinese males (n=28) and females (n=25) had body composition and aBMD (total body, lumbar spine, dual femur) assessed by DXA, and bone geometry (4%, 38%, 66%) of the non-dominant tibia measured by pQCT. Leg strength (two-leg press) and power (jump mat) and maximal grip strength (handgrip dynamometer) were measured. RESULTS: There were no sex differences in physical activity or calcium intake. After adjusting for height and weight, males had significantly greater leg press 1RM, grip strength, jump height, jump time, lumbar spine aBMD, 4% total BMC, 4% total area, and 4% bone strength index (BSI) (p<0.05) than females. In males, leg 1RM was positively correlated with total body aBMD (r= 0.427), and left femoral neck aBMD (r=0.445), and jump power was positively correlated with total body aBMD (r=0.580) and all hip aBMD variables (r=.487 to 0.646) (all p< 0.05). Females generally had stronger correlations between muscle and bone variables: leg 1RM (all p<0.05) and jump power (all p<0.003) were positively related to all aBMD variables (r=0.432 to 0.819). Jump power and BSI were positively correlated (r=0.378, p=0.048) in males, whereas jump power and leg 1RM showed moderate to strong correlations with 4% total BMC, total area, and total BSI (r=0.460 to 0.836, p<0.05) in females. CONCLUSION: Based on our findings, Chinese males had greater bone size, bone strength, and muscle strength than females; however, females exhibited more and stronger relationships between muscle and bone variables than males.Table 1: Sex Differences in Muscle and Bone variables (unadjusted Means ± SD)

Lower and Upper Body Muscle Characteristics among Collegiate Baseball and Soccer Players

Increased muscular strength in athletes has shown a prolific effect in the development of sports skills including jumping, throwing, sprinting, and change of direction abilities. Sports, such as soccer and baseball, differ largely in specific characteristics needed for success. To date, few studies have reported differences in sports specific skills between these two sports to measure and quantify the neuromechanical capacity. PURPOSE: To compare both lower and upper body strength among collegiate baseball (BB) and soccer (SC) players. METHODS: In this non-randomized cross-sectional study, 19 baseball and 19 soccer players, age ranges from 18-25 years completed the protocols. Lower body strength and power were assessed by a two-leg press maximal strength test (1RM) and vertical jump test (Just Jump Mat, Tendo Sports Machine), respectively. Upper body strength was assessed by a handgrip (HG) test using handgrip dynamometry (Takei, Japan). RESULTS: Independent sample t-test showed BB players (88.05 ± 7.1 kg) were significantly heavier than SC players (72.1 ± 7.2 kg) (p<0.05). However, weight-adjusted upper body strength and leg power were not significantly different between the two groups. BB players had significantly higher jump height (JH), time in air, and 1RM leg strength compared to SC players (p<0.05). CONCLUSIONS: BB players showed significantly higher lower muscle strength compared to SC players, however no differences were observed for peak power. These results provide a quantitative measure of the performance difference between these two sports, reinforcing the need for further research along with large sample size to assess the possible differences in training effectiveness and inherent characteristics between BB and SC players.Table 1: Athlete Performance Variables (Adjusted Mean ± SE)

Anthropometric Characteristics of Female and Male Athletes Bear A Different Effect on Fitness

Background: Anthropometric variables are highly related to physical performance, being used for the control and monitoring of athletes in different sports. However, whether anthropometric characteristics of female and male athletes bear a different effect on fitness must be determined. Objectives: To relate anthropometric characteristics and fitness of female in comparison with male athletes. Methods: College athletes (n = 189, 112 males) were assessed in weight, height, body mass index, lower and upper body power, agility, and endurance. Results: Males had greater weight and height than female athletes (17 kg and 17 cm, respectively), as well as fitness performance in all tests. In both males and females upper body power was positively correlated with body mass and height (P < 0.05). In addition, agility was negatively correlated (P < 0.05) with height in males and body mass in females. Aerobic fitness show a negative correlation (P < 0.05) with body mass in males. Conclusions: Anthropometric characteristics of female and male athletes bear a different effect on fitness.

Repeated-Sprint Ability in Division I Collegiate Male Soccer Players: Positional Differences and Relationships With Performance Tests

Lockie, RG, Moreno, MR, Orjalo, AJ, Stage, AA, Liu, TM, Birmingham-Babauta, SA, Hurley, JM, Torne, IA, Beiley, MD, Risso, FG, Davis, DL, Lazar, A, Stokes, JJ, and Giuliano, DV. Repeated-sprint ability in Division I collegiate male soccer players: positional differences and relationships with performance tests. J Strength Cond Res 33(5): 1362-1370, 2019-Repeated-sprint ability (RSA) in essential for soccer. Important considerations when assessing RSA is whether there are differences between positions (defenders, midfielders, and forwards), and what physiological characteristics may contribute to RSA. This has not been assessed in collegiate male players. Eighteen Division I male field players from one school performed several performance tests. The RSA test involved 7 × 30-m sprints completed on 20-second cycles. Measurements included total time (TT), and performance decrement (percent change in time from the first to last sprint; PD). Subjects also completed tests of lower-body power (vertical [VJ] and standing broad jump [SBJ]); linear (30-m sprint; 0-5 m, 0-10 m, 0-30 m intervals) and change-of-direction (505) speed; and soccer-specific endurance (Yo-Yo Intermittent Recovery Test Level 2; YYIRT2). A one-way analysis of variance (p < 0.05) determined between-position differences, and effect sizes were calculated. Pearson's correlations (p < 0.05) calculated relationships between RSA TT and PD with the other tests. There were no significant between-position differences for any test. There were large effects for the faster right-leg 505 and greater YYIRT2 distance for midfielders compared with defenders and forwards. Nonetheless, no between-position differences in RSA TT and PD were documented. There were relationships between RSA TT and the VJ (r = -0.59), SBJ (r = -0.61), 0-10 m (r = 0.64) and 0-30-m (r = 0.83) sprint intervals. There were no significant correlations for RSA PD. Male field players from one collegiate soccer team can demonstrate similar RSA across different positions. Greater lower-body power and sprinting speed could augment RSA.

Lower-body power in boxers is related to activity during competitive matches

ABSTRACTThe aim of this study was to create an activity profile of high-level boxing performance and to identify associations between boxers’ lower-body power capabilities and their activity profile. Eight high-level boxing athletes participated in the study. Lower-body power capabilities were calculated from counter-movement jumps (CMJs) and squat jumps (SJs) using a force plate. The boxing performance analysis consisted of 30 different variables gathered from 18 bouts from various international matches. The results demonstrated that boxing athletes delivered 22.3 ± 5.3 punches per min. The effectiveness of head punches was 14.3 ± 3.9%. CMJ height was correlated with the total number of punches thrown to the body and SJ height with rear-hand hooks (r = 0.735 and r = 0.793, respectively). The rate of SJ force development was correlated with the straight rear-hand punches (r = 0.751) and head punches effectiveness (r = 0.750). SJ peak power was inversely correlated with total stop frequency (r = – 0.786). In conclusion, the athletes who displayed higher power values in the CMJ and SJ tests were also more active during competitive bouts and accumulated less stoppage time during the competitive boxing bouts. More explosive boxers had higher effectiveness of head punches.

Influence of Playing Standard on Upper- and Lower-Body Strength, Power, and Velocity Characteristics of Elite Rugby League Players.

Background: To compare load–velocity and load–power relationships among first grade (n = 26, age 22.9 ± 4.3 years), academy (n = 23, age 17.1 ± 1.0 years), and scholarship (n = 16, age 15.4 ± 0.5 years) Super League rugby league players. Methods: Participants completed assessments of maximal upper- and lower-body strength (1RM) and peak velocity and power at 20, 40, 60, and 80 kg during bench press and squat exercises, in a randomised order. Results: Bench press and squat 1RM were highest for first grade players compared with other standards (effect size (ES) = −0.43 to −3.18). Peak velocities during bench and squat were greater in the higher playing standards (ES = −0.39 to −3.72 range), except for the squat at 20 and 40 kg. Peak power was higher in the better playing standards for all loads and exercises. For all three groups, velocity was correlated to optimal bench press power (r = 0.514 to 0.766), but only 1RM was related to optimal power (r = 0.635) in the scholarship players. Only squat 1RM in the academy was related to optimal squat power (r = 0.505). Conclusions: Peak velocity and power are key physical qualities to be developed that enable progression from junior elite rugby league to first grade level. Resistance training should emphasise both maximal strength and velocity components, in order to optimise upper- and lower-body power in professional rugby league players.

Comparison of Physical Fitness and Anthropometrical Profiles Among Brazilian Female Soccer National Teams From U15 to Senior Categories.

Ramos, GP, Nakamura, FY, Penna, EM, Mendes, TT, Mahseredjian, F, Lima, AM, Garcia, ES, Prado, LS, and Coimbra, CC. Comparison of physical fitness and anthropometrical profiles among Brazilian female soccer national teams from U15 to senior categories. J Strength Cond Res 35(8): 2302-2308, 2021-This study aimed to compare anthropometric and physical fitness of Brazilian female national team soccer players from the U15 to senior categories, and to compare the physical performance between selected and nonselected players. Subjects included 231 athletes (U15, n = 46, U17, n = 49, U20, n = 98, and Senior, n = 38). Body mass, height, sum of skinfolds, squat jump (SJ), countermovement jump (CMJ), 20-m linear sprint, and Yo-Yo IR1 were assessed. The U15 players were shorter than all other groups (p < 0.01) and lighter than U20 players (p < 0.01). Regarding physical tests, Senior athletes presented higher SJ compared with U20, and both showed higher CMJ and SJ compared with the U15 and U17 (p < 0.05). Senior athletes were also faster than players of all other categories in 20-m sprint (p < 0.01) and covered the greatest distance in the Yo-Yo IR1 (p < 0.05). U20 were better in the Yo-Yo IR1 than the younger groups (p < 0.05). When comparing selected and nonselected players, no differences were identified in anthropometric measures (p > 0.05). However, selected players from U17, U20, and Senior teams showed better performance in Yo-Yo IR1 than nonselected ones (p < 0.05). Finally, selected senior athletes also presented higher CMJ and SJ than nonselected players (p < 0.05). These results suggest that, although there is a tendency for maintenance in anthropometric measures from the age of 15 years, there are substantial improvements in speed, lower-body power, and aerobic capacity from U20 age group. In addition, it seems that intermittent aerobic fitness contributes to the selection of players to international tournaments in national teams.

Changes Over a Decade in Anthropometry and Fitness of Elite Austrian Youth Soccer Players.

Increases in physical (e.g., high-intensity running and sprinting), technical (e.g., passing rate), and tactical (e.g., player density) aspects made elite level soccer more challenging within the past years. The aim of the study was to evaluate whether these evolutions are also been reflected in changes in anthropometric and fitness characteristics between former (2002 to 2005) and current (2012 to 2015) elite Austrian youth development center (U13 to U14) and soccer academy (U15 to U18) players. A battery of anthropometric, general and soccer-specific fitness tests was conducted annually at the end of each year. Independent t-test and Cohen’s d (ES) were calculated to compare the two four-year periods (2530 vs. 2611 players) at each age group separately. Current players were significantly faster in 20 m sprint (ES = 0.26–0.50) and reaction test (ES = 0.15–0.39, except for U18), but less flexible at sit-and-reach (ES = –0.19 to –0.55), in all age categories. Whereas height (ES = 0.26–0.32), body mass (ES = 0.11–0.18) and countermovement jump (ES = 0.24–0.26) increased significantly at youth development center level, current academy players performed superior at shuttle sprint (ES = 0.21–0.59), hurdles agility run (ES = 0.24–0.49), and endurance run (ES = 0.11–0.20). These changes over time in speed, change-of-direction ability, lower-body power, coordination, and endurance were attributed to modern training approaches (e.g., modified games and change-of-direction drills) and modifications in selection politics (e.g., coaches favor speed and decision-making skills).

The Effect of In-Season Demands on Lower-Body Power and Fatigue in Male Collegiate Hockey Players.

Whitehead, PN, Conners, RT, and Shimizu, TS. The effect of in-season demands on lower-body power and fatigue in male collegiate hockey players. J Strength Cond Res 33(4): 1035-1042, 2019-The purpose of this study was to determine the effect of in-season demands, such as games, travel, and the subsequent fatigue related to these demands, on lower-body power (LBP) in collegiate hockey players. Two jump protocols (countermovement and squat jumps) were used to calculate LBP. Twenty-seven NCAA (National Collegiate Athletic Association) Division I male hockey players (age, 21.9 ± 1.4 years; height, 176.7 ± 6.5 cm; body mass, 81.4 ± 7.9 kg) participated in the study that spanned 18 weekly sessions. At each session, participants completed an 8-item fatigue questionnaire, which provided a cumulative numerical value for fatigue (total score of fatigue [TSF]), before performing maximal jumps on a contact mat. General linear modeling was conducted to compare dependent variables (jump height, relative LBP, TSF) across weekly sessions. Pearson product-moment correlation coefficients were calculated to examine the relationship between jump height and LBP across the jump protocols, as well as to examine the relationship of TSF with all measured variables. Jump height and LBP declined throughout the season with greater effect of travel observed following the longest travel sequence (p ≤ 0.05; η ≥ 0.60). Differences in TSF were observed from baseline (p ≤ 0.037), and a large effect was seen for away trips that included air travel (d ≥ 1.35). Total score of fatigue had a negative correlation with jump height and power during both jumps (r ≤ -0.742; p < 0.001). In conclusion, the in-season demands of ice hockey resulted in significant reductions in LBP throughout a hockey season, and the 8-item fatigue questionnaire is a sensitive tool reflective of athletic performance measures.

A Systematic Review of the Efficacy of Lower Body Aquatic Plyometric Training: The Development of Evidence-Based Recommendations for Practitioners

Objectives: Plyometric exercises are often prescribed for enhancing athletic performance, however, this form of training can elicit significant skeletal loading which may defer practitioners from utilizing these exercises throughout rehabilitation. Purpose: 1) complete a systematic review to critically examine the efficacy of plyometric training performed in water when compared to land for eliciting changes in musculoskeletal markers of performance, and 2) to provide evidence-based recommendations for practitioners on how best to utilize this form of training in rehabilitation and return-to-play. Methods: A systematic review was undertaken with relevant studies identified that compared changes in performance markers (e.g., strength, sprinting, and jumping) between the same aquatic- and land-based plyometric program were eligible for inclusion. Data was extracted using a standardized extraction form as confirmed by three reviewers. Data extraction included population characteristics, program design, and pre- and post- adaptations in strength, speed, and vertical jump. Results: Eight studies were included comparing performance outcomes following aquatic- and land-based plyometric training. The results of this review suggest that aquatic plyometric training is as effective as land-based plyometric training at improving lower body strength, sprint, and vertical jump performance. Conclusions: The utilization of aquatic plyometric training can be an important piece of the rehabilitation and return-to-play process in order to improve lower body strength, speed, and power while reducing the physical stress of land-based plyometric training.

Physical Qualities Pertaining to Shorter and Longer Change-of-Direction Speed Test Performance in Men and Women

This study investigated relationships between shorter (505, change-of-direction (COD) deficit as a derived physical quality) and longer (Illinois agility test; IAT) COD tests with linear speed, lower-body power (multidirectional jumping), and strength in recreationally-trained individuals. Twenty-one males and 22 females (similar to collegiate club-sport and tactical athletes) were assessed in: 505 and COD deficit from each leg; IAT; 20 m sprint; vertical jump (VJ height, peak anaerobic power measured in watts (PAPw), power-to-body mass ratio); standing broad jump; lateral jump (LJ) from each leg; and absolute and relative isometric midthigh pull (IMTP) strength. Partial correlations calculated sex-determined relationships between the COD and performance tests, with regression equations calculated (p < 0.05). The 505 and IAT correlated with all tests except PAPw and absolute IMTP (r = ±0.43–0.71). COD deficit correlated with the LJ (r = −0.34–0.60). Left- and right-leg 505 was predicted by sex, 20 m sprint, and left-leg LJ (70–77% explained variance). Right-leg COD deficit was predicted by sex and left-leg LJ (27% explained variance). IAT was predicted by sex, 20 m sprint, right-leg LJ, and relative IMTP (84% explained variance). For individuals with limited training time, improving linear speed, and relative lower-body power and strength, could enhance shorter and longer COD performance.

Cross-Sectional and Retrospective Cohort Analysis of the Effects of Age on Flexibility, Strength Endurance, Lower-Body Power, and Aerobic Fitness in Law Enforcement Officers.

Lockie, RG, Dawes, JJ, Kornhauser, CL, and Holmes, RJ. Cross-sectional and retrospective cohort analysis of the effects of age on flexibility, strength endurance, lower-body power, and aerobic fitness in law enforcement officers. J Strength Cond Res 33(2): 451-458, 2019-There can be a great age range in cohorts of law enforcement officers. As the tasks required of officers generally do not change with advancing age, it is important to understand how physical performance in tests that assess job-specific characteristics may be altered. Retrospective analysis of performance test data of 383 officers (362 men and 21 women) was conducted. The tests included the following: sit-and-reach to determine hamstring and lower back flexibility; maximal push-up and sit-up repetitions in 60 seconds to measure muscle endurance; vertical jump (VJ) to assess lower-body power; and 2.4-km run to ascertain aerobic capacity. Data were stratified by age into 20-29, 30-39, 40-49, and 50-59 year groups, and analyzed by sex. A 1-way analysis of variance with the Bonferroni post hoc test was used to calculate the differences between the groups. Considering the male subjects, the 40-49 and 50-59 year groups performed poorer in the VJ, sit-up test, and 2.4-km run compared with the 20-29 year group (p ≤ 0.001-0.045). For the female subjects, the 20-29 year group was superior to the 30-39 (p = 0.013) and 40-49 (p = 0.025) year groups in the push-up test. To ensure that an older officer can successfully complete occupation-specific tasks, lower-body power, abdominal strength, and aerobic training should be completed. Female officers should also attempt to maintain relative upper-body strength. Practitioners must attempt to design training programs that fit within the context of the occupational demands, and potentially using a nontraditional training design as law enforcement officers may not have the time to follow a traditional periodization model.

Assessing the Reliability of Using a Horizontal Leg Press Equipped With a Force Plate to Report on Measures of Positive and Negative Neuromuscular Characteristics.

Ferley, DD and Vukovich, MD. Assessing the reliability of using a horizontal leg press equipped with a force plate to report on measures of positive and negative neuromuscular characteristics. J Strength Cond Res 33(2): 360-371, 2019-Individuals participating in sport or returning from a lower-extremity injury routinely perform assessments of lower-body anaerobic capacity and power to gauge fitness or readiness to return to competition. However, many commonly used assessments lack the specificity of movement and muscle contraction demonstrated in sprinting, jumping, and changing direction. Therefore, this investigation assessed the reliability of a novel lower-body power test called a Plyo Press Power Quotient (3PQ), which involves jumping on a horizontal leg press equipped with a force plate. Thirty participants completed 1 repetition maximum (1RM) strength testing for 1 and 2 legs and a countermovement vertical jump. Two trials of 1- and 2-leg jump tests were performed using 30, 40, 50, and 60% of 1RM for 20 and 30 seconds, respectively. Dependent variables were a variety of positive (concentric) and negative (eccentric) neuromuscular indices. Statistical significance was set to p ≤ 0.05. No significant differences existed between trial 1 and 2 for any measures. One-way analysis of variance between %1RM conditions revealed significant differences in peak force (right; both), average negative power (left; right), average negative work (left; right), rate of power development (both), percent positive and negative fatigue (left; right; both), and velocity of movement (left; right; both). Peak power of all 2-leg jump tests correlated highly with vertical jump (r ≥ 0.89) but was significantly different. We conclude 3PQ testing provides a reliable assessment of anaerobic capacity and power, with the added benefit of easy single-leg comparisons.

Sex differences in competitive surfers' generic and specific strength capacity.

To compare the pop-up and counter movement jump (CMJ) and to analyse the relationships among the variables between sexes and different ages [under (U16), over (O16) 16 years] in male and female competitive surfers. Eighty-three surfers were divided according to sex, male (n = 55) and female (n = 28), and to age, U16 (n = 47) and O16 (n = 36). Vertical jump and pop-up movements were measured through the vertical ground reaction force with a force plate. CMJ demonstrated that the O16 male group exhibited significantly greater force compared to females in the concentric phase of the jump (CMJFMAX) (p < 0.01, ES = 1.82, large). Female U16 and O16 groups presented increased unloading rates in the eccentric phase compared to male surfers (CMJULR) (p < 0.05, ES = 0.73, moderate and p < 0.05, ES = 0.12, trivial, respectively). O16 males obtained significantly greater values than O16 females in the push-up phase (POPPUSH) (p < 0.05, ES = 0.76, moderate). Moderate correlations were found between lower-body power capacity and the pop-up (r = 0.32; ± 0.16 CL, p < 0.01, 98.1/1.9/0, very likely, moderate). General and skill-specific strengths are different in competitive male and female surfers, dependent upon their age range. The moderate association between CMJ and pop-up suggests that the pop-up might be influenced by other factors such as coordination or upper-body strength. Therefore, competitive surfers should also train the upper body strength and overall coordination in order to improve the performance of the pop-up movement.