Impact of Lower-Volume Training on Physical Fitness Adaptations in Team Sports Players: A Systematic Review and Meta-analysis

BACKGROUND

A small number of reviews have explored lower- versus higher-volume training in non-athletes, but the growing challenge of congested schedules in team sports highlights the need to synthesize evidence specific to team sport athletes. Thus, the objectives of this systematic review with meta-analysis are twofold: (i) to summarize the primary physiological and physical fitness outcomes of lower-volume versus higher-volume training interventions in team sports players; and (ii) to compare the effects of lower-volume training with higher, considering the training modalities used.

METHODS

We conducted searches across key databases, including PubMed, Scopus, SPORTDiscus, and Web of Science. We included team sports players with at least a trained or developmental level, focusing on studies comparing different training volumes (lower vs higher) within the same research. Lower volume training was defined in comparison to another load, emphasizing smaller training volume in terms of repetitions, duration, or frequency. The studies had to examine key physical performance adaptations and use two-arm or multi-arm designs. Methodological assessments of the included studies were performed using the Rob2 and ROBINS-I instruments, with evidence certainty evaluated through GRADE.

RESULTS

The initial search yielded 5,188 records, with 17 articles deemed eligible for the review. There was a non-significant trend favoring the higher-volume training group over the lower-volume group in resistance-based training when considering all pooled physical fitness outcomes (effect size - 0.05, 95% CI - 0.19 to 0.09, p = 0.506, I2 = 0.0%). A meta-analysis was not conducted for aerobic-based training due to only two studies being available, with one showing that lower volume training improved maximal oxygen uptake by 3.8% compared to 1.3% for higher volume, while the other indicated that lower training volumes enhanced performance by 1.6% versus 0.8%. The evidence certainty for physical performance outcomes was very low.

CONCLUSIONS

In newly introduced resistance training, lower volumes-regardless of repetitions or frequency-can achieve similar fitness gains to higher volumes. More pronounced tapering also appears more effective for supercompensation. However, the variability in study designs and training methods makes it difficult to establish a clear minimal dose. The main contribution of this review is mapping current research, providing a foundation for future studies and training optimization.

Curve sprint performance and speed-related capabilities in professional soccer players

BACKGROUND

In soccer, the capacity for acceleration and high-speed tasks extends beyond linear sprints to encompass a broad spectrum of multidirectional movements, including curvilinear sprints. We aimed to correlate mandatory speed-related capabilities with curve sprint (CS) performance in male professional soccer players.

METHODS

Twenty-one players (age 25.9 ± 5.4 years) performed the jump squat with 30% and 60% of body mass (JS30% and JS60%, respectively), countermovement (CMJ) and squat jumps (SJ), 10 m and 20 m linear sprint, 17 m CS, 20 m with change-of-direction (COD), and 20 m resisted sprints with 20% and 65% of body mass (RS20% and RS65%, respectively). The Pearson product-moment test and Spearman correlation test were performed.

RESULTS

Strong correlations were observed between 10 m (r = 0.662; p = 0.001) and 20 m (r = 0.677; p < 0.001) linear sprint times with CS times. Regarding the COD speed, moderate correlations with RS20% times (r = 0.508; p = 0.019) and very strong correlations with RS65% times (r = 0.750; p < 0.001) were observed. Moderate relationships were observed for CMJ with 20 m linear sprint times (r = - 0.467; p = 0.033) and CS times (r = - 0.471; p = 0.031), as well as for SJ and CS times (r = - 0.437; p = 0.047).

CONCLUSIONS

This information offers insights for enhancing test sensitivity and tailoring training prescriptions in professional soccer, once correlation was found between groups of tasks with vertical predominance (i.e., vertical jump, curved and linear sprints) and horizontal predominance (i.e., COD and resisted sprints).

The impact of landing forces on repeated jumping performance

BACKGROUND

High-velocity concentric actions can be negatively impacted by cumulative fatigue during plyometric training. Reducing vertical ground reaction forces (GRF) upon landing could decrease eccentric demands, potentially minimizing fatigue, maintaining concentric performance, and benefiting concentric training adaptations. Therefore, this study examined the effect of intentionally higher and lower landing vertical GRF on the ability to sustain concentric jumping performance.

METHODS

Twenty men (25.2±3.5 years) performed 30 maximal effort jumps over a 50 cm hurdle (high-landing GRF) and onto a 50 cm box (low-landing GRF), on two separate occasions in a counter-balanced order. Jumps were measured using two force platforms (one for takeoff and one for landing) and a linear position transducer. The 30 jumps were divided into 5 groups of 6 repetitions, and the mean value for each group was analyzed.

RESULTS

There was no significant condition × repetition group interaction for any parameters, indicating that the greater landing GRF during hurdle jumps did not negatively affect concentric jump performance throughout the 30 jumps. Concentric velocities and jump height were significantly greater during box jumps compared to hurdle jumps.

CONCLUSIONS

Thirty maximal-effort jumps did not cause fatigue-related decrease of performance, independent of jump type (i.e., the magnitude of landing GRF). Although, reduced vertical GRF upon landing appears to have a neutral-to-positive effect on concentric jumping performance. Therefore, reducing landing GRF, such as by using BJs, could acutely augment jumping performance and help to reduce cumulative training load.

Kinetic Analysis, Potentiation, and Fatigue During Vertical and Horizontal Plyometric Training: An In-Depth Investigation Into Session Volume

Despite previous support for plyometric training, optimal dosing strategies remain unclear.

PURPOSE

To investigate vertical and horizontal jump kinetic performance following a low-volume plyometric stimulus with progressively increased session jump volume.

METHODS

Sixteen academy rugby players (20.0 [2.0] y; 103.0 [17.6] kg; 184.3 [5.5] cm) volunteered for this study. Vertical and horizontal jump sessions were conducted 1 week apart and consisted of a 40-jump low-volume plyometric stimulus using 4 exercises, after which volume was progressively increased to 200 jumps, using countermovement jump (CMJ) for vertical sessions and horizontal broad jump (HBJ) for horizontal sessions. Jump performance was assessed via force-plate analysis at baseline (PRE-0), following the low-volume plyometric stimulus (P-40), and every subsequent 10 jumps until the end of the session (P-50, P-60, P-70, ... P-200).

RESULTS

The low-volume stimulus was effective in potentiating HBJ (2% to 5%) but not CMJ (0% to -7%) performance (P < .001). The HBJ performance enhancements were maintained throughout the entire high-volume session, while CMJ realized small but significant decrements (-5% to -7%) in jump height P-50 to P-80 before recovering to presession values. Moreover, increases in eccentric impulse (5% to 24%; P < .001) in both sessions were associated with decreased or maintained concentric impulse, indicating a breakdown in performance-augmenting mechanisms and less effective power transfer concentrically after moderate volumes.

CONCLUSION

Practitioners should consider kinetic differences between HBJ and CMJ with increasing volume to better inform and understand session dosing strategies.

Effects of Moderate-to-Heavy Sled Training Using Different Magnitudes of Velocity Loss in Professional Soccer Players

ABSTRACT

Grazioli, R, Loturco, I, Lopez, P, Setuain, I, Goulart, J, Veeck, F, Inácio, M, Izquierdo, M, Pinto, RS, and Cadore, EL. Effects of moderate-to-heavy sled training using different magnitudes of velocity loss in professional soccer players. J Strength Cond Res 37(3): 629-635, 2023-This study investigated the effects of a 11-week moderate-to-heavy sled training intervention with different magnitudes of velocity loss on sprint and jump performance, mechanical muscle function, and body composition in professional soccer players. Seventeen players (age 25.8 ± 4.3 years; height 180.0 ± 8.6 cm; mass 77.7 ± 9.7 kg) were randomly allocated into 2 groups, based on different magnitudes of velocity loss: 10% of velocity decrease (G10, n = 8) and 20% of velocity decrease (G20, n = 9). The velocity-based sled training consisted of 20-m resisted sprints with a progressive loading increase from 45 to 65% of body-mass throughout the intervention. Pre-intervention and postintervention sprint and jump performance, hamstring and quadriceps peak torque and isometric rate of torque development, and lower-limb lean mass measured by dual X-ray absorptiometry were assessed and compared. Two-way repeated measures analysis of variance revealed a significant time-effect for decreases in 10- and 20-m sprint times ( p = 0.018 and p = 0.033, respectively), but without a time-group interaction. The G10 showed greater beneficial effects than G20 for both 10-m (-5.5 ± 3.3%, magnitude-based inference [MBI]: possibly vs. -1.7 ± 5.9%, MBI: possibly trivial) and 20-m (-2.5 ± 2.1%, MBI: possibly vs. -1.4 ± 3.7%, MBI: likely trivial) sprint times. Moreover, there was a significant time effect for countermovement jump height and quadriceps isometric peak torque, which decreased significantly after training ( p = 0.019 and p = 0.010, respectively), with no within-group effect of time vs. group interaction for these respective outcomes. The novel velocity-based sled model proposed here, especially under lower magnitudes of velocity loss, was able to significantly improve linear sprint performance in professional soccer players.

Speed-Related Abilities Are Similarly Improved After Sled Training Under Different Magnitudes of Velocity Loss in Highly Trained Soccer Players

PURPOSE

We examined the effects of two 8-week resisted-sprint training programs under different magnitudes of velocity loss (VL) on the speed-related performance of highly trained soccer players.

METHODS

Twenty-one soccer players (age: 25.9 [5.4] y) were randomly assigned to 1 of 2 groups: (1) the "moderate-load group," players who trained with sled loads that induced 15%VL relative to unloaded sprint velocity (n = 11); and (2) the "heavy-load group," players who trained with sled loads that induced 40% VL relative to unloaded sprint velocity (n = 10). Linear sprint (10 m), curve sprint, change-of-direction speed, resisted-sprint performance at 15% VL and 40% VL, and vertical jumping ability were tested pretraining and posttraining. A 2-way repeated-measures analysis of variance was used to test for differences between groups. In addition, percentage changes were calculated for speed-related abilities and compared with their respective coefficients of variation to determine whether individual changes in performance were greater than the test variance (ie, "true change").

RESULTS

A main effect of time was detected for 10-m sprint, curve sprint, change-of-direction speed, and 15% VL and 40% VL resisted-sprint times, with significant decreases in sprint times (P = .003, P = .004, P = .05, P = .036, and P = .019, respectively). Jump variables did not change significantly over time. There were no group-by-time interactions for any tested variable (P > .05), but the "true change" analysis revealed meaningful individual changes in both groups.

CONCLUSIONS

Both moderate- and heavy-sled loading conditions may optimize the development of speed-related abilities in highly trained soccer players. Nevertheless, resisted-sprint training responses may differ meaningfully when assessed on an individual basis.

Effects of plyometric training on softer vs. Harder surfaces on jump-related performance in rugby sevens players

This study aimed to compare jump-related performance after plyometric training on harder vs. softer surfaces in rugby sevens players. Fourteen players were randomly assigned to the harder surface group (H-G, n = 7) and softer surface group (S-G, n = 7). Three times per week, in the morning, the players performed plyometric training on different surfaces and strength training. Before and after the 4-week intervention period, squat jump (SJ), countermovement jump (CMJ), and CMJ with arms (CMJA) tests were performed to measure vertical jump displacement (d), rate of force development (r), and power (p). The main results indicated a significant improvement in S-G for CMJd (∆% = +8.2%; p = 0.029; ES = 0.59) and for CMJAp (∆% = +8.7%; p = 0.035; ES = 0.44). These improvements were significant compared to H-G for CMJAd (F_1,12 = 8.50; p = 0.013; ηp2 = 0.41; ES = 0.83) and CMJAp (F_1,12 = 7.69; p = 0.017; ηp2 = 0.39; ES = 0.79). This study reveals that performance related to the counter movement jump with arms on softer surfaces after 4-week plyometric training improved vertical jump displacement and lower body power in rugby sevens players.

Acute Effects of "Composite" Training on Neuromuscular and Fast Stretch-Shortening Cycle Drop Jump Performance in Hurling Players

ABSTRACT

Byrne, PJ, Moody, JA, Cooper, SM, and Kinsella, S. Acute effects of "composite" training on neuromuscular and fast stretch-shortening cycle drop jump performance in hurling players. J Strength Cond Res 35(12): 3474-3481, 2021-"Composite" training is a term developed by the authors and defined as the combination of a plyometric exercise with an explosive activity such as a sprint run, performed as a "combined repetition"/session. The purposes of this study were to investigate the acute effect of a "composite" training session on neuromuscular and fast stretch-shortening cycle bounce drop jumps (BDJs) in hurling players' immediately, after session, and after 7 days of recovery. Eight hurling players first completed a drop jump test to identify individual BDJ drop height, followed 72 hours later with a single "composite" training session. Three repetition maximum (3RM) back squat strength, BDJ, countermovement jump (CMJ), and sprint performance testing were performed 10 minutes before and immediately after session and 7 days after session. An analysis of variance reported a significant decrease in CMJ measures (height, velocity, and eccentric rate of force development) and sprint performance from presession to postsession (p ≤ 0.05). Moreover, a significant increase was evident for CMJ performance (height and power), sprint performance (5 and 20 m), 3RM back squat strength, and BDJ performance (reactive strength index and height) from postsession to post-7-day recovery (p ≤ 0.05). Pairwise comparisons indicated that absolute and relative 3RM strength significantly increased from presession to post-7 days (absolute 3RM: p = 0.0001; relative 3RM: p = 0.01). The findings indicate that "composite" training results in an immediate decline in CMJ measures after session possibly due to acute muscle fatigue, and supercompensation augments maximum lower-limb strength after 7 days of recovery.

Rate of Force Development as an Indicator of Neuromuscular Fatigue: A Scoping Review

Because rate of force development (RFD) is an emerging outcome measure for the assessment of neuromuscular function in unfatigued conditions, and it represents a valid alternative/complement to the classical evaluation of pure maximal strength, this scoping review aimed to map the available evidence regarding RFD as an indicator of neuromuscular fatigue. Thus, following a general overview of the main studies published on this topic, we arbitrarily compared the amount of neuromuscular fatigue between the "gold standard" measure (maximal voluntary force, MVF) and peak, early (≤100 ms) and late (>100 ms) RFD. Seventy full-text articles were included in the review. The most-common fatiguing exercises were resistance exercises (37% of the studies), endurance exercises/locomotor activities (23%), isokinetic contractions (17%), and simulated/real sport situations (13%). The most widely tested tasks were knee extension (60%) and plantar flexion (10%). The reason (i.e., rationale) for evaluating RFD was lacking in 36% of the studies. On average, the amount of fatigue for MVF (-19%) was comparable to late RFD (-19%) but lower compared to both peak RFD (-25%) and early RFD (-23%). Even if the rationale for evaluating RFD in the fatigued state was often lacking and the specificity between test task and fatiguing exercise characteristics was not always respected in the included studies, RFD seems to be a valid indicator of neuromuscular fatigue. Based on our arbitrary analyses, peak RFD and early phase RFD appear even to be more sensitive to quantify neuromuscular fatigue than MVF and late phase RFD.

Implementation and Efficacy of Plyometric Training: Bridging the Gap Between Practice and Research

ABSTRACT

Watkins, CM, Storey, A, McGuigan, M, and Gill, ND. Implementation and efficacy of plyometric training: Bridging the gap between practice and research. J Strength Cond Res 35(5): 1244-1255, 2021-Plyometric training is an effective method for improving speed and acceleration. However, a gap seems to exist between research recommendations and practitioner's actual programs. Some reports suggest as many as 400 jumps per session, while anecdotally some strength and conditioning coaches are using as few as 15-40 jumps even with elite athletes. Thus, the purposes of this study were to obtain a clearer understanding of the practitioner's perspective on plyometric training strategies as compared to literary recommendations and to compare any trends across competition level or sport categories. An integrative mixed-methods model was used. Globally, 61 strength and conditioning practitioners completed an anonymous online survey, containing 5 sections: 1. Sport and coaching background information, 2. Plyometric training focus, 3. Periodization strategy, 4. Plyometric program details, and 5. Efficacy of plyometrics for sport performance. Questions included yes/no, multiple choice, Likert scale, percentage-based, and open-ended questions. The majority (70.5%) of respondents reported regularly implementing plyometric training and overwhelmingly (96.7%) reported positive athlete feedback surrounding its perceived efficacy. Findings confirmed that many practitioners regularly use significantly lower session volumes than previous literary recommendations (p < 0.05). In addition, significant differences were noted in many program details across competition level and sport category including volume periodization, exercise choice, and plyometric intensity. Practitioners may want to reflect on these reported group differences when building training programs best suited for their athletes. Meanwhile, future research should consider these reported perspectives when formulating interventions in attempts of bridging the gap between practice and theory.

The Effect of Low-Volume Preseason Plyometric Training on Force-Velocity Profiles in Semiprofessional Rugby Union Players

ABSTRACT

Watkins, CM, Gill, ND, Maunder, E, Downes, P, Young, JD, McGuigan, MR, and Storey, AG. The effect of low-volume preseason plyometric training on force-velocity profiles in semiprofessional rugby union players. J Strength Cond Res 35(3): 604-615, 2021-Rugby union is a physically demanding and complex team sport requiring athletes across all positions to express speed and acceleration. Plyometrics can effectively improve speed profiles by enhancing both force- and velocity-(FV) characteristics; however, the optimal dose and exercise direction for trained athletes is still relatively unknown. Therefore, the aim of this investigation was to determine the efficacy of a low-dose, directionally specific plyometric training program for improving speed profiles in semiprofessional rugby players. Players were randomly allocated to one of 2 plyometric training groups that performed low-volume (40-60 ground contacts per session) plyometrics twice weekly, or a control group that did not participate in any plyometric training. The 2 training groups underwent reverse back-to-back three-week vertically and horizontally focused plyometric training programs, with a 12-day washout. Body composition, aerobic capacity, and sprint performance (10-, 20-, 30-m split time, horizontal FV profile) were measured. During the intervention, HV-1 (horizontal/vertical training group 1) improved sprint performance (n = 12; ∆30 m = -0.020 seconds; p = 0.038), VH-2 (vertical/horizontal training group 2) maintained sprint performance (n = 8; ∆30 m = +0.049 seconds; p = 0.377), and the control group progressively declined in sprint performance (n = 12; ∆30 m = +0.071; p = 0.019). In addition, vertical plyometrics may preferentially benefit secondary acceleration (∆10-20 m split time: -0.01 seconds; p = 0.03) and many force-oriented FV profile characteristics. Correlational analyses (r2 = -0.568 to 0.515) showed sprint improvements were hindered in athletes with lower initial aerobic fitness, suggesting accumulated fatigue may have limited the magnitude of adaptation. Therefore, including low-volume plyometric training may be beneficial for improving sprint profiles or attenuating decrements realized during periods of high-volume sport-specific training.

Moderate volume of sprint bouts does not induce muscle damage in well-trained athletes

INTRODUCTION

Understanding the recovery in response to different sprint protocols is important for optimizing neuromuscular gains and organizing training sessions in sports. The current study aimed to investigate acute neuromuscular changes following a moderate volume of sprint protocols with and without change-of-direction.

METHODS

26 well-trained male collegiate athletes from different sports were randomly allocated into straight-line group (SLG) or change-of-direction group (CODG). The protocols were 1 × 15 repetitions of 20-meter sprints in line (SLG) or with two changes in each repetition (CODG). Knee extension maximal and explosive strength, jump performance, serum creatine kinase, and quadriceps and hamstrings echo intensity were collected pre-, post- 0, 24, 48, and 72 h post-exercise.

RESULTS

There were no significant changes in any of the variables at any time point after the exercise protocols in comparison with pre-exercise values (p > 0.05).

CONCLUSIONS

The present study suggests that sprint training with moderate volume with or without change of direction does not induce neuromuscular or physiological changes during 72 h post-exercise. This information is especially important for sports staff in order to optimize training prescription and frequency.

Is Tensiomyography-Derived Velocity of Contraction a Sensitive Marker to Detect Acute Performance Changes in Elite Team-Sport Athletes?

PURPOSE

To examine the variations in the velocity of contraction (Vc) assessed using tensiomyography, vertical jumping ability, and sprinting speed induced by 4 different exercise protocols (ie, strength, sprint, plyometric, and technical training sessions) in 14 male national-team rugby players (age 21.8 [2.6] y, weight 83.6 [8.5] kg, and height 177.4 [6.7] cm).

METHODS

Physical tests were conducted immediately before and after 4 distinct workouts in the following order: tensiomyography in the rectus femoris and biceps femoris muscles, squat and countermovement jumps, and 30-m sprint velocity. To analyze the differences in the assessed variables before and after each training session, the differences based on magnitudes were calculated.

RESULTS

After strength and plyometric workouts, the players presented possible to almost certain impairments in sprint and jump performance and in the Vc of the rectus femoris (effect sizes 0.26-0.64). After the sprint-training session, possible to very likely decreases were observed in the squat jump, 30-m sprint, and Vc of the biceps femoris (effect sizes 0.21-0.44). By contrast, after the technical training, athletes demonstrated a possible increase in the squat jump and Vc in both muscles examined (effect sizes 0.13-0.20).

CONCLUSIONS

The main finding of this research is that, for the vast majority of results, the direction of changes observed in Vc were the same as those observed in performance assessments. This suggests that Vc might be used as a sensitive marker of acute variations in speed and power performance of elite team-sport athletes.

Blood lactate responses to plyometric training in cricket players of different maturity level: a randomised controlled trial

Previous studies commonly examined the acute effect of plyometric exercise on blood lactate. To the best of our knowledge, no study has examined the effect of short-term plyometric training on blood lactate levels of cricket players. To investigate the effect of an 8 week plyometric training program on blood lactate concentration in cricket players of different maturity level. 55 healthy male cricket players (aged 14-35 years) were categorised into 14-17, 18-25 and 26-35 groups. Blood lactate concentration (BLAC) was assessed before and after 8 weeks of the intervention period. Regardless of the maturity level, a significant reduction in BLAC was observed in the experimental cricketers (P<0.05) in response to 8 weeks of training. Blood lactate responses did not vary significantly in 14-17, 18-25 and 26-35 groups of cricket players following plyometric training. Plyometric training significantly reduced BLAC in cricket players despite non-significant differences amongst 14-17, 18-25 and 26-35 groups. Plyometric training could be recommended for adolescent (14-17) and adult cricketers (18-25 and 26-35) for improving their physiological capacities so as to develop optimal performance.

Efficacy of complex training on angular velocity of shoulder in collegiate basketball players

BACKGROUND

Shoulder internal rotation angular velocity at the time of ball release is a crucial factor deciding the ball velocity in throwing. Even though there are some studies conducted regarding the effectiveness of complex training on the lower limb, the researchers has not given much attention to the upper limb.

OBJECTIVE

To investigate the efficacy of a complex training program combining plyometric and weight training on the angular velocity of shoulder with a program composed of only plyometric training or only weight training.

METHODS

It was a pre-test - post-test experimental study. Thirty healthy male collegiate basketball players were randomly divided into three groups: Plyometric training group (n= 10), weight training group (n= 10), complex training group which includes both plyometric training and weight training (n= 10). The training was given for six weeks with a frequency of two days per week. Subjects were measured for angular velocity of shoulder before and after the training period by using Biodex upper body cycle. All the three groups were compared by using one way ANOVA. Post-hoc fisher least significant difference (LSD) test was used to find out the difference between groups.

RESULTS

All the groups showed a significant gain in angular velocity after the six-week training period (p< 0.05). However, the improvement attained in complex training group were significantly greater than other training groups (p< 0.05).

CONCLUSION

The study concluded that a combination of plyometric and weight training (complex training) can improve the angular velocity of shoulder in male collegiate basketball players more than plyometric or weight training alone.

BEHAVIOR OF CORTISOL, CK AND LACTATE IN A SESSION OF VARIABLE RESISTANCE

ABSTRACT Introduction: Complex Training (CT) has been used to achieve Post-activation Potentiation (PAP) of physical capabilities and, in doing so, improve the sports performance of athletes. However, few studies have considered alterations in serum Cortisol, Metabolic Creatine Kinase (MB-CK), Total Creatine Kinase (Total-CK), and Lactate concentrations ([La]) resulting from this training method. Objective: This study determined the behavior of the following blood serum substances in a CT session: Cortisol, MB-CK, Total CK and [La]. Method: Ten military athlete volunteers aged 28.5 ± 4.8 years; 66.2 ± 2.8 kg, 171.4 ± 3.7 cm, 22.6 ± 1.2 kg/m2; 11.3 ± 2.9% of fat tissue took part in the study. The study had a quasi-experimental, intrasubject design. The variable measurements were: Cortisol, MB-CK, Total-CK, and [La], measured before physical exercise and 24 hours post-stress. The CT session consisted of: four series of five repetitions at 30% of 1RM, plus four repetitions at 60% of 1RM, plus three throws of a 575 g projectile, 15 seconds apart. The statistical analysis was carried out through repeated measure ANOVA for Lactate and a Wilcoxon Matched Pairs t-Test for Cortisol, MB-CK and Total-CK. Results: There was no evidence of alterations in the indicators for fatigue ([La] p = 0.36), and muscular injury (Cortisol p = 0.16; MB-CK p = 0.23; Total-CK p = 0.64) after the training sessions. Conclusion: Variables for muscular injury showed no evidence of alterations 24 hours after the CT sessions, hence confirming that the workload did not generate significant post-stress muscular injury. Level of Evidence I; Therapeutic Study: Investigating Treatment Results.

Effect of upper body plyometric training on physical performance in healthy individuals: A systematic review

OBJECTIVE

To determine the impact of upper body plyometric training (UBPT) on physical performance parameters such as strength, ball throwing speed, ball throw distance and power in healthy individuals.

METHODS

PubMed, Scopus, ResearchGate and ERIC databases were searched up to August 2017. Selection of articles was done if they described the outcomes of an upper body plyometric exercise intervention; included measures of strength, ball throwing speed, ball throw distance, or power; included healthy individuals; used a randomized control trial; and had full text available in English language. The exclusion criteria were unpublished research work and clubbing of UBPT with some other type(s) of training apart from routine sports training. PEDro scale was used to rate the quality of studies eligible for this review.

RESULTS

Initially 264 records were identified and out of them only 11 articles met the eligibility criteria and were selected (PEDro score = 4 to 6). Though large to very small effects observed in improving ball throwing velocity, ball throwing distance, power and strength of upper limb muscles after UBPT, the results should be implemented with caution.

CONCLUSION

Inconclusive results obtained preclude any strong conclusion regarding the efficacy of UBPT on physical performance in healthy individuals.

The Neuromuscular, Biochemical, and Endocrine Responses to a Single-Session Vs. Double-Session Training Day in Elite Athletes

Johnston, MJ, Cook, CJ, Drake, D, Costley, L, Johnston, JP, and Kilduff, LP. The neuromuscular, biochemical, and endocrine responses to a single-session vs. double-session training day in elite athletes. J Strength Cond Res 30(11): 3098-3106, 2016-The aim of this study was to compare the acute neuromuscular, biochemical, and endocrine responses of a training day consisting of a speed session only with performing a speed-and-weights training session on the same day. Fifteen men who were academy-level rugby players completed 2 protocols in a randomized order. The speed-only protocol involved performing 6 maximal effort repetitions of 50-m running sprints with 5 minutes of recovery between each sprint, whereas the speed-and-weights protocol involved the same sprinting session but was followed 2 hours later by a lower-body weights session consisting of 4 sets of 5 backsquats and Romanian deadlift at 85% one repetition maximum. Testosterone, cortisol, creatine kinase, lactate, and perceived muscle soreness were determined immediately before, immediately after, 2 hours after, and 24 hours after both the protocols. Peak power, relative peak power, jump height, and average rate of force development were determined from a countermovement jump (CMJ) at the same time points. After 24-hours, muscle soreness was significantly higher after the speed-and-weights protocol compared with the speed-only protocol (effect size η = 0.253, F = 4.750, p ≤ 0.05). There was no significant difference between any of the CMJ variables at any of the posttraining time points. Likewise, creatine kinase, testosterone, and cortisol were unaffected by the addition of a weight-training session. These data indicate that the addition of a weight-training session 2 hours after a speed session, whereas increasing the perception of fatigue the next day does not result in a difference in endocrine response or in neuromuscular capability.

Neuromuscular Fatigue and Physiological Responses After Five Dynamic Squat Exercise Protocols

This aimed to analyze neuromuscular, physiological and perceptual responses to a single bout of 5 different dynamic squat exercise protocols. In a randomized and counterbalanced order, 15 male resistance-trained athletes (mean ± SD; age: 23.1 ± 1.9 years, body mass: 77.4 ± 8.0 kg) completed traditional multiple sets (MS: 4 × 6, 85% 1 repetition maximum [RM]), drop sets (DS: 1 × 6, 85% 1RM + 3 drop sets), eccentric overload (EO: 4 × 6, 70% 1RM concentric, 100% 1RM eccentric), flywheel YoYo squat (FW: 4 × 6, all-out), and a plyometric jump protocol (PJ: 4 × 15, all-out). Blood lactate (La), ratings of perceived exertion (RPE), counter movement jump height (CMJ), multiple rebound jump (MRJ) performance, maximal voluntary isometric contraction force, serum creatine kinase (CK) and delayed onset muscle soreness were measured. Immediately post exercise, La was significantly (p < 0.001) higher in FW (mean ± 95% confidence limit; 12.2 ± 0.9 mmol·L) and lower in PJ (3.0 ± 0.8 mmol·L) compared with MS (7.7 ± 1.5 mmol·L), DS (8.5 ± 0.6 mmol·L), and EO (8.2 ± 1.6 mmol·L), accompanied by similar RPE responses. Neuromuscular performance (CMJ, MRJ) significantly remained decreased (p < 0.001) from 0.5 to 48 hours post exercise in all protocols. There was a significant time × protocol interaction (p ≤ 0.05) in MRJ with a significant lower performance in DS, EO, and FW compared with PJ (0.5 hours post exercise), and in EO compared with all other protocols (24 hours post exercise). A significant main time effect with peak values 24 hours post exercise was observed in CK serum concentrations (p < 0.001), but there was no time × protocol interaction. In conclusion, (a) metabolic and perceptual demands were higher in FW and EO compared with MS, DS and PJ, (b) neuromuscular fatigue was consistent up to 48 hours post exercise in all protocols, and

Age at Time of Initial Sexual Intercourse and Health of Adolescent Girls

Adolescence is characterized by marked changes in the body, psychology, and sexual behavior due to increasing production of hormones. In this review we aimed to assess the effect of age at the time of first sexual intercourse (sexarche) on the health of adolescent girls, and identify factors that might protect against early initiation of sexual relations in girls. The PubMed, Lilacs, and Google Scholar databases were searched for clinical trials, comparative studies, case-control studies, cross-sectional studies, cohort studies, multicenter studies, observational studies, meta-analyses, and systematic reviews published up to December 2014 on this theme. The search terms were: "sexual debut," "coitarche," "sexarche," and "young people," "adolescent," "unplanned pregnancy," "adolescent contraception," and "STDs." Data were extracted from 28 studies and 41 references were used to introduce the theme and to support the discussion. Sexarche has been occurring in increasingly younger girls. A young age at sexarche can lead to subsequent risky sexual behavior. Girls who have sexarche when they are 14 years old or younger are less likely to use contraception on this occasion, take more time before they start using contraception in subsequent sexual relations, are more likely to have several sex partners, have a higher risk for depression, have lower self-esteem and more episodes of repentance, and have a higher risk for a sexually transmitted disease and cervical cancer. Girls with low educational, socioeconomic, and cultural status, little parental monitoring, parental separation, and absence of religiosity tend to experience sexarche at a younger age. Adolescent girls who postpone sexarche until they are 16 years old are physically and psychologically healthier than those who have sexarche at a younger age. This suggests that providing adolescent girls with appropriate education about sexual relations might reduce the negative effect of sexual relations at a young age.

Effect of two complex training protocols of back squats in blood indicators of muscular damage in military athletes

[Purpose] The aim of this study was to determine the variations in the blood muscular damage indicators post application of two complex training programs for back squats. [Subjects and Methods] Seven military athletes were the subjects of this study. The study had a quasi-experimental cross-over intra-subject design. Two complex training protocols were applied, and the variables to be measured were cortisol, metabolic creatine kinase, and total creatine kinase. For the statistical analysis, Student’s t-test was used. [Results] Twenty-four hours post effort, a significant decrease in cortisol level was shown for both protocols; however, the metabolic creatine kinase and total creatine kinase levels showed a significant increase. [Conclusion] Both protocols lowered the indicator of main muscular damage in the blood supply (cortisol). This proved that the work weight did not generate significant muscular damage in the 24-hour post-exercise period.

Salivary cortisol and testosterone responses to resistance and plyometric exercise in 12- to 14-year-old boys

This study examined changes in salivary testosterone and cortisol following resistance and plyometric exercise protocols in active boys. In a crossover experimental design, 26 peri-pubertal (12- to 14-year-old) soccer players performed 2 exercise trials in random order, on separate evenings, 1 week apart. Each trial included a 30 min control session followed by 30 min of either resistance or plyometric exercise. Saliva was collected at baseline, post-control (i.e., pre-exercise), and 5 and 30 min post-exercise. There were no significant differences in the baseline hormone concentrations between trials or between weeks (p > 0.05). A significant effect for time was found for testosterone (p = 0.02, [Formula: see text] = 0.14), which increased from pre-exercise to 5 min post-exercise in both the resistance (27% ± 5%) and plyometric (12% ± 6%) protocols. Cortisol decreased to a similar extent in both trials (p = 0.009, [Formula: see text] = 0.19) from baseline to post-control and then to 5 min post-exercise, following its typical circadian decrease in the evening hours. However, a significant protocol-by-time interaction was observed for cortisol, which increased 30 min after the plyometrics (+31% ± 12%) but continued to decrease following the resistance protocol (-21% ± 5%). Our results suggest that in young male athletes, multiple modes of exercise can lead to a transient anabolic state, thus maximizing the beneficial effects on growth and development, when exercise is performed in the evening hours.