Effects of stretching on performances involving stretch-shortening cycles

Effects of chronic static stretching interventions on jumping and sprinting performance-a systematic review with multilevel meta-analysis

When improving athletic performance in sports with high-speed strength demands such as soccer, basketball, or track and field, the most common training method might be resistance training and plyometrics. Since a link between strength capacity and speed strength exists and recently published literature suggested chronic stretching routines may enhance maximum strength and hypertrophy, this review was performed to explore potential benefits on athletic performance. Based on current literature, a beneficial effect of static stretching on jumping and sprinting performance was hypothesized. A systematic literature search was conducted using PubMed, Web of Science and Google scholar. In general, 14 studies revealed 29 effect sizes (ES) (20 for jumping, nine for sprinting). Subgroup analyses for jump performance were conducted for short- long- and no stretch shortening cycle trials. Qualitative evaluation was supplemented by performing a multilevel meta-analysis via R (Package: metafor). Significant positive results were documented in six out of 20 jump tests and in six out of nine sprint tests, while two studies reported negative adaptations. Quantitative data analyses indicated a positive but trivial magnitude of change on jumping performance (ES:0.16, p = 0.04), while all subgroup analyses did not support a positive effect (p = 0.09-0.44). No significant influence of static stretching on sprint performance was obtained (p = 0.08). Stretching does not seem to induce a sufficient stimulus to meaningfully enhance jumping and sprinting performance, which could possibly attributed to small weekly training volumes or lack of intensity.

Assessment of Fatigue and Recovery in Sport: Narrative Review

Fatigue is a phenomenon associated with decreases in both physical and cognitive performances and increases in injury occurrence. Competitive athletes are required to complete demanding training programs with high workloads to elicit the physiological and musculoskeletal adaptations plus skill acquisition necessary for performance. High workloads, especially sudden rapid increases in training loads, are associated with the occurrence of fatigue. At present, there is limited evidence elucidating the underlying mechanisms associating the fatigue generated by higher workloads and with an increase in injury risk. The multidimensional nature and manifestation of fatigue have led to differing definitions and dichotomies of the term. Consequently, a plethora of physiological, biochemical, psychological and performance markers have been proposed to measure fatigue and recovery. Those include self-reported scales, countermovement jump performance, heart rate variability, and saliva and serum biomarker analyses. The purpose of this review is to provide an overview of fatigue and recovery plus methods of assessments.

Acute effects of long-lasting stretching and strength training on maximal strength and flexibility in the calf muscle

The so-called “stretch-induced force deficit” is known from a large amount of research. There are many theories trying to explain the stretch-induced force deficit and increases in the range of motion (ROM) which all offer a stretch training-specific explanation. However, when performing a commonly used strength training session, a reduced maximum strength (MSt) capacity can be assumed as well. Based on this, the aim of the study is to investigate the tension-induced force deficit due to a suprathreshold strength or stretching training stimulus. Therefore, 71 participants (age: 24.1 ± 4.2 years, height: 176.3 ± 5.7 cm, weight: 74.1 ± 7.5 kg) were divided into three groups: static stretching group (SST), strength training group (STR), and control group (CG). To investigate possible mechanical tension-induced force deficits, SST performed a long-lasting static stretching intervention for 1 h using an orthosis, while STR executed a common strength training intervention (5 × 12 repetition) for the plantar flexors. The results show a significant reduction of measured MSt as well as increased ROM for both SST and STR following the interventions. Consequently, we found similar acute effects of stretching and strength training regarding MSt and flexibility. We conclude that the decreased MSt capacities can possibly be attributed to mechanical tension-induced damage of the muscle that is not linked to a specific training method. The improvements in flexibility found in both intervention groups might be attributed to warm up effects when inducing high mechanical tension to large ankle joint angles.

The effect of two different stretching exercises on the muscle tendon unit and range of motion

BACKGROUND: Stretching is commonly used for clinical and sports reason but the effects vary on time and the technique used. PURPOSE: To determine the acute effects of static and dynamic stretching of gastrocnemius muscle on muscle-tendon unit (MTU) and dorsiflexion range of motion (ROM) in the same individuals; to find out how long the stretching effects endure. METHODS: Twenty-eight males (mean age: 22.18 ± 2.58 years) were included in the study. A 45-s static stretching (SS) exercise was applied to the right leg 5 times and dynamic stretching (DS) of same duration to the other leg. Change in MTU was assessed by ultrasonography and active and passive ROM was measured with goniometer. All evaluations were performed before, immediately following, 5-min, 15-min and 30-min after stretching. RESULTS: Muscle thickness and pennation angle did not change over time with either techniques (p> 0.05). A significant muscle-tendon junction (MTJ) displacement occurred after the techniques (p< 0.05); the highest change was achieved after DS (p< 0.05). Both techniques improved active ROM values similarly (p< 0.05), but only dynamic stretching increased passive ROM significantly (p< 0.05). Active and passive ROM and MTJ displacement values at 30th – min were still higher than the baseline ones on the DS side (p< 0.05). However, SS increased active ROM angle immediately after application but this increment declined until the final measurement. CONCLUSION: We recommend using the dynamic stretching technique to achieve greater and longer lasting increases in tendon length and range of motion.

Time-based effects of different duration stretching on calf muscle strength

BACKGROUND: There are conflicting reports on the acute effects of stretching on muscle strength. Some studies report reduction in muscle strength however others report no change following stretching. OBJECTIVE: To assess the acute effects of static stretching (SS) of different durations on the isometric maximum voluntary contraction force (MVCF) of the calf muscle. METHODS: Pretest-posttest experimental design was used. Ten male participants (mean age 25.4 ± 2.11 years) participated in three experimental trials: SS for 2-minutes (SS2), 4-minutes (SS4), and 8-minutes (SS8). MVCF was measured before, immediately after, at 10- and 20-minutes post-stretch intervals. Each SS trial involved varied repetitions of 30-seconds stretches and 20-seconds relaxation periods. The isometric maximum voluntary contraction force (MVCF) was the outcome measure. RESULTS: SS2, SS4, and SS8 did not change the MVCF at 0-, 10- and 20-minutes post stretching intervals (p> 0.05). CONCLUSIONS: 2-, 4-, and 8-minutes intermittent SS did not change the isometric muscle strength in the Calf muscle up to 20 minutes after stretching and thus can safely be performed before those sporting events that require significant muscle strength.

Are Strength Indicators and Skin Temperature Affected by the Type of Warm-Up in Paralympic Powerlifting Athletes?

(1) Background: the present study aimed to evaluate the effect of different types of warm-ups on the strength and skin temperature of Paralympic powerlifting athletes. (2) Methods: the participants were 15 male Paralympic powerlifting athletes. The effects of three different types of warm-up (without warm-up (WW), traditional warm-up (TW), or stretching warm-up (SW)) were analyzed on static and dynamic strength tests as well as in the skin temperature, which was monitored by thermal imaging. (3) Results: no differences in the dynamic and static indicators of the force were shown in relation to the different types of warm-ups. No significant differences were found in relation to peak torque (p = 0.055, F = 4.560, η2p = 0.246 medium effect), and one-repetition maximum (p = 0.139, F = 3.191, η2p = 0.186, medium effect) between the different types of warm-ups. In the thermographic analysis, there was a significant difference only in the pectoral muscle clavicular portion between the TW (33.04 ± 0.71 °C) and the WW (32.51 ± 0.74 °C) (p = 0.038). The TW method also presented slightly higher values than the SW and WW in the pectoral muscles sternal portion and the deltoid anterior portion, but with p-value > 0.05. (4) Conclusions: the types of warm-ups studied do not seem to interfere with the performance of Paralympic Powerlifting athletes. However, the thermal images showed that traditional warm-up best meets the objectives expected for this preparation phase.

Effects of 6-Week Static Stretching of Knee Extensors on Flexibility, Muscle Strength, Jump Performance, and Muscle Endurance

ABSTRACT

Ikeda, N and Ryushi, T. Effects of 6-week static stretching of knee extensors on flexibility, muscle strength, jump performance, and muscle endurance. J Strength Cond Res 35(3): 715-723, 2021-The purpose of this study was to evaluate the changes in flexibility and muscular performance after stretching training for 6 weeks. Twelve healthy young men were assigned to a stretching group and 13 to a control group. The subjects of the stretching group performed static stretching of knee extensors for 6 weeks. Knee flexion range of motion (KFROM), leg extension strength, rate of force development (RFD) in leg extension, jump performance (squat and countermovement jump height, and index of rebound jump), and strength decrement index of 50 repetitions of isokinetic knee extension (muscle endurance) were measured before and after the interventions. In the stretching group, KFROM significantly increased from 145.2 ± 17.3 to 158.7 ± 6.3° (p < 0.05), whereas RFD significantly improved from 10,173 ± 2,401 to 11,883 ± 2,494 N·s-1 (p < 0.05). By contrast, leg extension strength and jump performance of each jump type did not improve significantly. Furthermore, muscle endurance decreased significantly. All variables remained unchanged in the control group. In conclusion, 6 weeks of stretching training of knee extensors improved KFROM and RFD in leg extension, but not leg extension strength and jump performance; moreover, muscle endurance decreased. These findings indicate that this stretching training protocol can be used by athletes in sports who require high flexibility and those who require high-power exertion.

Evidence-based post exercise recovery in combat sports: a narrative review

INTRODUCTION

Some methods such as ergo nutritional aids, cooling or massage among others could improve recovery in combat sports (CS). The effects, doses, duration, and timing of these methods remains unknown. Nowadays, there is no clear consensus regarding the recovery strategies and it is necessary to understand the type of fatigue induced in CS and its underlying mechanisms. The main aim of this article is to review the update literature related to recovery strategies in CS.

EVIDENCE ACQUISITION

A literature search was conducted following preferred reporting items for review statement on the topic of: "combat sports," "recovery," "nutrition," "fatigue," "ergogenic aids," "weight cutting" and "hydration."

EVIDENCE SYNTHESIS

The initial search of the literature detected 369 articles about CS. Later, 307 were excluded after being determined unrelated to recovery or after failure to fulfill the inclusion criteria. Of the 80 included articles, 19 satisfied the final inclusion criteria.

CONCLUSIONS

To optimize CS performance, adequate recovery is required during training and competition processes. Traditional ergo nutritional supplementation of carbohydrates and proteins combined. Besides, the consumption of evidence supported supplementation (green tea, beetroot gels, creatine or alkaline water) improve recovery processes. Further methods of recovery including physical (cold water immersion, massage or photobiomodulation) and physiological (types of active recovery, sleep and rest) therapies have also been shown useful. This narrative review elucidates the important role of recovery techniques in CS.

The Influence of Warm-Up on Body Temperature and Strength Performance in Brazilian National-Level Paralympic Powerlifting Athletes

Background and Objectives: The effects of warm-up in athletic success have gained strong attention in recent studies. There is, however, a wide gap in awareness of the warm-up process to be followed, especially in Paralympic powerlifting (PP) athletes. This study aimed to analyze different types of warm-up on the physical performance of PP athletes. Materials and Methods: The sample consisted of 12 elite Brazilian PP male athletes (age, 24.14 ± 6.21 years; bodyweight, 81.67 ± 17.36 kg). The athletes performed maximum isometric force (MIF), rate of force development (RFD), and speed test (Vmax) in three different methods of warm-up. Tympanic temperature was used to estimate the central body temperature. Results: A significant difference was observed for MIF in the without warm-up (WW) condition in relation to the traditional warm-up (TW) and stretching warm-up (SW) (p = 0.005, η²_p = 0.454, high effect). On the contrary, no significant differences were observed in RFD, fatigue index (FI) and time in the different types of warm up (p > 0.05). Furthermore, no significant differences were observed in relation to the maximum repetition (p = 0.121, η²_p = 0.275, medium effect) or the maximum speed (p = 0.712, η²_p = 0.033, low effect) between the different types of warm up. In relation to temperature, significant differences were found for the TW in relation to the “before” and “after” conditions. In addition, differences were found between WW in the “after” condition and SW. In addition, WW demonstrated a significant difference in relation to TW in the “10 min later” condition (F = 26.87, p = 0.05, η²_p = 0.710, high effect). Conclusions: The different types of warm-up methods did not seem to provide significant differences in the force indicators in elite PP athletes.

Does the inclusion of ballistic exercises during warm-up enhance short distance running performance?

BACKGROUND

Warm-up is considered essential to optimize running performance, but little is known about the effect of specific warm-up tasks, specifically in the real competitive context. The current study aimed to verify the acute effects of a warm-up including ballistic exercises in 30m running performance. In addition, a second 30m trial was assessed to better understand the warm-up effects in training/competition.

METHODS

Twenty-two men (19.32±1.43 years-old) randomly completed the time-trials on separate days and after a typical warm-up (WU), a WU complemented with ballistic exercises (postactivation potentiation [PAP]) or no warm-up (NWU). Biomechanical, physiological and psychophysiological variables were assessed.

RESULTS

The participants were 1.9% faster in the first 30m sprint after WU compared with NWU, mainly increased performance in the first 15m (P=0.03, ES=0.48). WU resulted in greater stride length in the last 15m of the first sprint. PAP did not differ from NWU and WU, despite eight participants performed better after this warm-up.

CONCLUSIONS

These results highlight the positive effects of warm-up for sprinting, despite failed to evidence positive effects when ballistic exercises are included. In addition, the influence of warm-up in the running technique was highlighted by the changes in the running kinematics and a need for individualization of warm-up procedures.

The stretch-shortening cycle efficiency is dependent on the maturational stage

Abstract Maturation interferes with physiological and mechanical aspects of muscle contraction. The aim of the present study was to compare the efficiency of the stretch-shortening cycle (SSC) between different maturation stages. One hundred forty six young people, with 72 boys and 74 girls, were recruited to participate in the study. Sexual maturation was measured and the group was stratified into adolescents (> 3 auto-tanner) and children (<2 auto-tanner). Squat jump (SJ) and countermovement jump (CMJ) performance were measured to measure reactive force (RF) capacity, eccentric utilization ratio (EUR) and pre-stretch augmentation (PSAP). The children did not present statistical difference between SJ and CMJ (t(55)= -1.93; ∆ = -0.61; 95% CI = -1.24 to -0.02; p = 0.058), while the adolescents presented higher performance of CMJ (t(89)= -12.28; ∆ = -2.44; 95% CI = -2.84 to -2.05; p <0.001). In addition, adolescents had higher RF performance (t(144)= 5.18; p <0.0001; 95% CI = 2.53 to 1.13), PSAP (t(144)= 4.38; p <0.0001; 95% CI = 14.00 to 5.29) and EUR (t(144)= 4.38; p <0.0001; 95% CI = 0.14 to 0.05). We conclude that more mature young people have better SSC utilization.

Acute Effects of Static Stretching on Muscle Strength and Power: An Attempt to Clarify Previous Caveats

The effects of static stretching (StS) on subsequent strength and power activities has been one of the most debated topics in sport science literature over the past decades. The aim of this review is (1) to summarize previous and current findings on the acute effects of StS on muscle strength and power performances; (2) to update readers’ knowledge related to previous caveats; and (3) to discuss the underlying physiological mechanisms of short-duration StS when performed as single-mode treatment or when integrated into a full warm-up routine. Over the last two decades, StS has been considered harmful to subsequent strength and power performances. Accordingly, it has been recommended not to apply StS before strength- and power-related activities. More recent evidence suggests that when performed as a single-mode treatment or when integrated within a full warm-up routine including aerobic activity, dynamic-stretching, and sport-specific activities, short-duration StS (≤60 s per muscle group) trivially impairs subsequent strength and power activities (∆1–2%). Yet, longer StS durations (>60 s per muscle group) appear to induce substantial and practically relevant declines in strength and power performances (∆4.0–7.5%). Moreover, recent evidence suggests that when included in a full warm-up routine, short-duration StS may even contribute to lower the risk of sustaining musculotendinous injuries especially with high-intensity activities (e.g., sprint running and change of direction speed). It seems that during short-duration StS, neuromuscular activation and musculotendinous stiffness appear not to be affected compared with long-duration StS. Among other factors, this could be due to an elevated muscle temperature induced by a dynamic warm-up program. More specifically, elevated muscle temperature leads to increased muscle fiber conduction-velocity and improved binding of contractile proteins (actin, myosin). Therefore, our previous understanding of harmful StS effects on subsequent strength and power activities has to be updated. In fact, short-duration StS should be included as an important warm-up component before the uptake of recreational sports activities due to its potential positive effect on flexibility and musculotendinous injury prevention. However, in high-performance athletes, short-duration StS has to be applied with caution due to its negligible but still prevalent negative effects on subsequent strength and power performances, which could have an impact on performance during competition.

Impact of 10-Minute Interval Roller Massage on Performance and Active Range of Motion

Hodgson, DD, Quigley, PJ, Whitten, JHD, Reid, JC, and Behm, DG. Impact of 10-minute interval roller massage on performance and active range of motion. J Strength Cond Res 33(6): 1512-1523, 2019-Roller massage (RM) has been shown to increase range of motion (ROM) without subsequent performance deficits. However, prolonged static stretching (SS) can induce performance impairments. The objective of this study was to examine the effects of combining SS and RM with and without subsequent RM on ROM and neuromuscular performance. Subjects (n = 12) participated in 5 sessions: (a) SS only (SS_rest), (b) SS + RM (SS + RM_rest), (c) SS with RM at 10 and 20 minutes after stretch (SS_RM), (d) SS + RM with RM at 10 and 20 minutes after stretch (SS + RM_RM), and (e) control. For the SS conditions, the quadriceps and hamstrings received passive SS for 2 × 30 seconds each. For the SS + RM conditions, SS was applied to the quadriceps and hamstrings for 30 seconds each, and RM was performed for 30 seconds per muscle. SS_RM and SS + RM_RM conditions received an additional 30-second RM at 10 and 20 minutes after warm-up, whereas sessions without additional RM rested for the same duration. Testing measures included hip flexion (HF) and knee flexion (KF) active and passive ROM, hurdle jump height and contact time, countermovement jump height, and maximal voluntary isometric contraction force. Initial KF and HF ROM improvements provided by SS_RM and SS + RM_RM were sustained up to 30 minutes after intervention. Furthermore, SS_RM exhibited greater ROM compared with sessions lacking additional RM in active and passive HF as well as active and passive KF. Similarly, SS + RM_RM elicited greater KF and HF ROM improvements than SS_rest. In conclusion, active KF and HF ROM improvements were prolonged by additional RM, whereas neuromuscular performance remained relatively unaffected.

The Effect of Ballistic Exercise as Pre-Activation for 100 m Sprints

The benefits of warm-up in sports performance has received a special interest in the current literature. However, there is a large gap of knowledge about the tasks to be performed, specifically in the real competitive environment. The purpose of the study was to verify the acute effects of a warm-up including ballistic exercises in 100 m running performance. In addition, a second 100 m trial was assessed to better understand the warm-up effects in training and competition. Eleven men (25.4 ± 6.2 years of age, 1.76 ± 0.08 m of height, 78.2 ± 8.6 kg of body mass) were submitted to three different protocols, in a randomized order: no warm-up (NWU), typical warm-up (WU) and WU complemented with ballistic exercises (PAP). Biomechanical, physiological and psychophysiological variables were assessed. Differences were found between the three conditions assessed in the first 100 m sprint with 7.4% and 7.6% faster performances after the WU and PAP, compared to NWU. Stride length was higher in the second part of the 100 m after PAP compared with WU. These results highlight the positive effects of warm-up for sprinting performance. The inclusion of ballistic exercises, besides being used to improve sprint performance, can increase stride length in the final of the 100 m race.

Acute Effect of Dynamic Stretching on Endurance Running Performance in Well-Trained Male Runners

The purpose of this study was to clarify the acute effect of dynamic stretching (DS) on relative high-intensity endurance running performance. The endurance running performances of 7 well-trained middle- or long-distance male runners were assessed on a treadmill after 2 types of pretreatment. The pretreatments were nonstretching (NS) and DS treatment. In the DS treatment, DS was performed as 1 set of 10 repetitions as quickly as possible for the 5 muscle groups in lower extremities. The endurance running performances were evaluated by time to exhaustion (TTE) and total running distance (TRD) during running at a velocity equivalent to 90% maximal oxygen uptake (VO2max) in each subject. The oxygen uptake (VO2) during running was measured as an index of running economy (RE). The TTE (928.6 ± 215.0 seconds) after DS treatment was significantly (p < 0.01) more prolonged compared with that (785.3 ± 206.2 seconds) after NS. The TRD (4,301.2 ± 893.8 m) after DS treatment was also significantly (p < 0.01) longer than that (3,616.9 ± 783.3 m) after NS. The changes in the VO2 during running, however, did not significantly (p > 0.05) differ between the pretreatments. The results demonstrated that the DS treatment improved the endurance performance of running at a velocity equivalent to 90% VO2max in well-trained male runners, although it did not change the RE. This running velocity is equivalent to that for a 3,000- or 5,000-m race. Our finding suggests that performing DS during warm-up before a race is effective for improving performance.

Elastography Study of Hamstring Behaviors during Passive Stretching

INTRODUCTION

The mechanical properties of hamstring muscles are usually inferred from global passive torque/angle relationships, in combination with adjoining tissues crossing the joint investigated. Shear modulus measurement provides an estimate of changes in muscle-tendon stiffness and passive tension. This study aimed to assess the passive individual behavior of each hamstring muscle in different stretching positions using shear wave elastography.

METHODS/RESULTS

The muscle shear modulus of each hamstring muscle was measured during a standardized slow passive knee extension (PKE, 80% of maximal range of motion) on eighteen healthy male volunteers. Firstly, we assessed the reliability of the measurements. Results were good for semitendinosus (ST, CV: 8.9%-13.4%), semimembranosus (SM, CV: 10.3%-11.2%) and biceps femoris long-head (BF-lh, CV: 8.6%-13.3%), but not for biceps femoris short-head (BF-sh, CV: 20.3%-44.9%). Secondly, we investigated each reliable muscle in three stretch positions: 70°, 90° and 110° of hip flexion. The results showed different values of shear modulus for the same amount of perceived stretch, with the highest measurements in the high-flexed hip situation. Moreover, individual muscles displayed different values, with values increasing or BF-lh, SM and ST, respectively. The inter-subject variability was 35.3% for ST, 27.4% for SM and 30.2% for BF-lh.

CONCLUSION

This study showed that the hip needs to be high-flexed to efficiently tension the hamstrings, and reports a higher muscle-tendon stress tolerance at 110° of hip angle. In addition muscles have different passive behaviors, and future works will clarify if it can be linked with rate of injury.

Health-Related Physical Fitness in Healthy Untrained Men: Effects on VO2max, Jump Performance and Flexibility of Soccer and Moderate-Intensity Continuous Running

The purpose of this study was to determine the effects of recreational soccer (SOC) compared to moderate-intensity continuous running (RUN) on all health-related physical fitness components in healthy untrained men. Sixty-nine participants were recruited and randomly assigned to one of three groups, of which sixty-four completed the study: a soccer training group (SOC; n = 20, 34±4 (means±SD) years, 78.1±8.3 kg, 179±4 cm); a running group (RUN; n = 21, 32±4 years, 78.0±5.5 kg, 179±7 cm); or a passive control group (CON; n = 23, 30±3 years, 76.6±12.0 kg, 178±8 cm). The training intervention lasted 12 weeks and consisted of three 60-min sessions per week. All participants were tested for each of the following physical fitness components: maximal aerobic power, minute ventilation, maximal heart rate, squat jump (SJ), countermovement jump with arm swing (CMJ), sit-and-reach flexibility, and body composition. Over the 12 weeks, VO2max relative to body weight increased more (p<0.05) in SOC (24.2%, ES = 1.20) and RUN (21.5%, ES = 1.17) than in CON (-5.0%, ES = -0.24), partly due to large changes in body mass (-5.9, -5.7 and +2.6 kg, p<0.05 for SOC, RUN and CON, respectively). Over the 12 weeks, SJ and CMJ performance increased more (p<0.05) in SOC (14.8 and 12.1%, ES = 1.08 and 0.81) than in RUN (3.3 and 3.0%, ES = 0.23 and 0.19) and CON (0.3 and 0.2%), while flexibility also increased more (p<0.05) in SOC (94%, ES = 0.97) than in RUN and CON (0-2%). In conclusion, untrained men displayed marked improvements in maximal aerobic power after 12 weeks of soccer training and moderate-intensity running, partly due to large decreases in body mass. Additionally soccer training induced pronounced positive effects on jump performance and flexibility, making soccer an effective broad-spectrum fitness training intervention.

Alternative Countermovement-Jump Analysis to Quantify Acute Neuromuscular Fatigue

Purpose:

To examine the reliability and magnitude of change after fatiguing exercise in the countermovement-jump (CMJ) test and determine its suitability for the assessment of fatigue-induced changes in neuromuscular (NM) function. A secondary aim was to examine the usefulness of a set of alternative CMJ variables (CMJ-ALT) related to CMJ mechanics.

Methods:

Eleven male college-level team-sport athletes performed 6 CMJ trials on 6 occasions. A total of 22 variables, 16 typical (CMJ-TYP) and 6 CMJ-ALT, were examined. CMJ reproducibility (coefficient of variation; CV) was examined on participants’ first 3 visits. The next 3 visits (at 0, 24, and 72 h postexercise) followed a fatiguing high-intensity intermittent-exercise running protocol. Meaningful differences in CMJ performance were examined through effect sizes (ES) and comparisons to interday CV.

Results:

Most CMJ variables exhibited intraday (n = 20) and interday (n = 21) CVs of <10%. ESs ranging from trivial to moderate were observed in 18 variables at 0 h (immediately postfatigue). Mean power, peak velocity, flight time, force at zero velocity, and area under the force–velocity trace showed changes greater than the CV in most individuals. At 24 h, most variables displayed trends toward a return to baseline. At 72 h, small increases were observed in time-related CMJ variables, with mean changes also greater than the CV.

Conclusions:

The CMJ test appears a suitable athlete-monitoring method for NM-fatigue detection. However, the current approach (ie, CMJ-TYP) may overlook a number of key fatigue-related changes, and so practitioners are advised to also adopt variables that reflect the NM strategy used.