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Force-time curve of a countermovement jump. An example of a force-time curve of a countermovement jump (CMJ). The eccentric and concentric phase are displayed. RFD, Rate of Force Development. Full-size DOI: 10.7717/peerj.10044/fig-2
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The present randomized cross-over controlled study aimed to compare the rate of recovery from a strength-oriented exercise session vs. a power-oriented session with equal work. Sixteen strength-trained individuals conducted one strength-oriented session (five repetitions maximum (RM)) and one power-oriented session (50% of 5RM) in randomized order....
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Context 1
... jump's phases were calculated as follows: Duration (s) of the SJ was found by backtracking force data from take-off (force <2 N) to the point where the force was 101.5% of body weight. CMJ was divided into an eccentric phase and a concentric phase (Fig. 2), defined by the phase where the COM was descending and ascending, respectively. The initiation of the CMJ (eccentric phase) was found by backtracking the force data from the point of zero velocity, i.e., the deepest position of the COM, to the point where the force was 98.5% of body weight. Eccentric peak force was the highest force ...
Context 2
... the force data from the point of zero velocity, i.e., the deepest position of the COM, to the point where the force was 98.5% of body weight. Eccentric peak force was the highest force measured within the eccentric phase, and eccentric time was defined as the duration of the eccentric phase where the force was greater than that of the body weight (Fig. 2). Peak concentric force was the highest force measured from the point of zero velocity of the COM to the point of ...
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... maximal rate of force development (RFD) was defined as the largest increase in force over a 5 ms time window during the jump (both for SJ and CMJ; Fig. 2). Specifically, the RFD values (N/s) were calculated from numerical differentiation of the low-pass filtered force measurements using a 4-point method, and the derivative was averaged over 5 ms (10 samples). In the MJ test, the participants were instructed to jump ten consecutive CMJs as high as possible. The vertical stiffness was ...
Citations
... Therefore, the structure and order of each training session within a microcycle may have an influence on recovery, and performance in subsequent training sessions, which summate to produce better outcomes over the course of a full mesocycle. These acute programming benefits may be due to greater neuromuscular impairments and recovery times seen after a strength compared to a power session (Helland et al., 2020) and thus, it is speculated that by placing an "easier" day in between two "harder" days as opposed to having two "hard" days in a row, individuals may be able to perform better throughout the week. However, outcomes may vary for individuals based on their training background which can also influence acute responses, thus, warranting sport specific and individual-specific consideration (Kotikangas et al., 2022). ...
Systemic resistance training aims to enhance performance by balancing stress, fatigue and recovery. While fatigue is expected, insufficient recovery may temporarily impair performance. The aim of this review was to examine evidence regarding manipulation of resistance training variables on subsequent effects on recovery and performance. PubMed, Medline, SPORTDiscus, Scopus and CINAHL were searched. Only studies that investigated recovery between resistance training sessions were selected, with a total of 24 articles included for review. Training to failure may lengthen recovery times, potentially impairing performance; however, it may be suitable if implemented strategically ensuring adequate recovery between sessions of similar exercises or muscle groups. Higher volumes may increase recovery demands, especially when paired with training to failure, however, with wide variation in individual responses, it is suggested to start with lower volume, monitor recovery, and gradually increase training volume if appropriate. Exercises emphasising the lower body, multi-joint movements, greater muscle recruitment, eccentric contractions, and/or the lengthened position may require longer recovery times. Adjusting volume and frequency of these exercises can affect recovery demands depending on the goals and training logistics. Daily undulating programming may maximise performance on priority sessions while maintaining purposeful and productive easy days. For example, active recovery in the form of training opposing muscle groups, light aerobic cardio, or low-volume power-type training may improve recovery and potentially elicit a post activation potentiation priming effect compared to passive recovery. However, it is possible that training cessation may be adequate for allowing sufficient recovery prior to sessions of importance.
... Given the increase in volume that xRM testing entails, it is plausible that a greater level of fatigue will be induced and therefore preparedness will be suppressed for an elongated period of time. 14,15 Moreover, the fact that xRM testing is performed to volitional failure may lead one to hypothesize that the possible increased levels of fatigue associated with this practice will exacerbate the variability of an athlete's strength levels on a day-to-day basis. 2 Whether this is the case, however, remains unknown. This presents a conundrum for strength and conditioning professionals wishing to use results from dynamic strength tests such as a 3RM or five repetition maximum (5RM) to prescribe training loads, as fluctuations in strength over the course of a microcycle may result in them inadvertently over or under-loading the athlete in relation to their capacity on a given day. 2 As such, the primary aims of the study was to determine whether the 3RM deadlift changed over the course of a microcycle and the impact of repeated lower-body strength testing on commonly used measures of preparedness such as the CMJ and barbell velocity during submaximal warm-up sets. ...
This study investigated the stability of three repetition maximum strength during the deadlift. Eleven participants performed four testing sessions comprising a one-repetition maximum test and three 3RM tests separated by 48 hours. Preparedness was assessed before each testing session using countermovement jumps and by measuring barbell velocity during each set of deadlifts. Trivial statistically significant differences were determined for the 3RM between T1 and both T2 (p = 0.012; ES [95% CI] = -0.1 [-0.58, 0.41]) and T3 (p = 0.027; ES [95% CI] = -0.09 [-0.57, -0.43]). No significant differences were noted between T2 and T3 (p = 0.595; ES [95% CI] = 0.01 [-0.49, 0.50]). No significant differences in jump height (p = 0.071), time-to-take-off (p = 0.862), eccentric displacement (p = 0.209), or mean force during any CMJ sub-phase were found between each session (p = 0.529 – 0.913). Small differences in barbell mean velocity were found between both T1-T2 (ES = -0.21-0.27) and T2-T3 (ES = 0.31-0.48), while trivial differences were found at others. Therefore, 3RM deadlift strength appears stable enough over a microcycle to continue using traditionally recommended heavy/light programming strategies.
... The higher level of soreness after HRT, as reflected by the lower PRS, possibly resulted in a lower force generation capability [35]. Previous studies with similar HRT protocols also showed impaired strength performance 24 h after training, which was attributed to both central and peripheral fatigue [15,18,36]. It was also indicated that HRT might require up to 72 h for a neuromuscular function to recover fully [36]. ...
... Findings from previous studies investigating the acute effect of HRT on CMJ performance have shown conflicting results, with some showing no changes [17,37], while others showing a decrease in CMJ height and other performance measures [15,16,33]. This discrepancy is likely due to the different training protocols adopted by the different studies. ...
... This discrepancy is likely due to the different training protocols adopted by the different studies. Based on the findings from Helland et al. [15] and Raeder et al. [33], CMJ height decreased by 4.5-8.2 cm at Post 5min and 3.2-3.7 cm at Post 24h . ...
Purpose This study compared the acute effects of a session of isometric strength training (ISO) with heavy resistance training (HRT) training on 20-m sprint, countermovement jump (CMJ) and isometric mid-thigh pull (IMTP) performance. Methods Ten resistance-trained athletes (age: 26.7 ± 6.2 years, body mass: 71.5 ± 16.2 kg, height: 1.68 ± 0.10 m) performed baseline measures for 20-m sprint, CMJ and IMTP prior to either an ISO or HRT session. During both training sessions, participants performed back squats, Romanian deadlift and split squat. Post-test performances were measured 5 min and 24 h after each training session. Participants returned a week later to perform the other training session. Results A significant time × condition effect was found for 20-m sprint time (P = 0.007) and IMTP peak force (P = 0.003). Main time effect was observed for 20-m sprint (P < 0.001), CMJ height (P < 0.001) and IMTP peak force (P < 0.001). HRT resulted in a greater increase in sprint time at 5 min (0.17 ± 0.12 vs. 0.06 ± 0.05 s, P = 0.013, g = 1.15) and 24 h (0.01 ± 0.09 vs. 0.00 ± 0.05 s, P = 0.004, g = 1.32) post-training as compared to ISO. Similarly, HRT resulted in a significantly larger reduction in IMTP peak force than ISO at both 5 min (− 363.3 ± 248.8 vs. − 98.9 ± 230.3 N, P = 0.024, g = 1.06) and 24 h (− 289.2 ± 256.2 vs. 37.9 ± 177.8 N, P = 0.004, g = 1.42) post-training. Total impulses generated during each exercise were greater during ISO than HRT (P < 0.001-0.006). Rating of perceived recovery post 24 h was higher in ISO than HRT (P = 0.002). Conclusion The above results indicated that acute HRT led to a greater reduction in sprinting strength performance and lower perceived recovery post-24 h than ISO.
... d z = 0.96) in resistancetrained individuals. Similar to our findings, current evidence (Byrne & Eston, 2002;Gathercole et al., 2015;Helland et al., 2020;Hiscock et al., 2018) indicates JH and PP tend to decrease at 24 hours after a resistance training session. For example, Helland et al. (Helland et al., 2020) confirmed that SJ, JH and PP significantly decreased 24 hours after a strength-oriented session in resistance-trained individuals (both, p < 0.05). ...
... Similar to our findings, current evidence (Byrne & Eston, 2002;Gathercole et al., 2015;Helland et al., 2020;Hiscock et al., 2018) indicates JH and PP tend to decrease at 24 hours after a resistance training session. For example, Helland et al. (Helland et al., 2020) confirmed that SJ, JH and PP significantly decreased 24 hours after a strength-oriented session in resistance-trained individuals (both, p < 0.05). Byrne and Eston (Byrne & Eston, 2002) also reported substantial SJ JH 33.8 ± 6.5 32.0 ± 6.6 32.3 ± 6.9 −6.0 ± 6.2%*(d z = 1.00) −5. ...
... decrements from baseline to 24, 48, and 72 hours after 10 sets of 10 back squats at 70% of the subject's BM (all p < 0.05) in moderately trained individuals. Thus, based on previous literature (Byrne & Eston, 2002;Gathercole et al., 2015;Helland et al., 2020;Hiscock et al., 2018) and our findings, maximum and nontime specific peak force and power measures may not be sensitive enough to measure acute fatigue, especially within the 48-hour window of a high-volume resistance training session. ...
The purposes of this study were to investigate the acute effects of resistance training protocol on kinetic changes in squat jump (SJ), shortened isometric mid-thigh pull (IMTP), and isometric squat (ISQ) and to examine the relationship of dynamic maximum strength with performance changes over 48 hours in resistance trained individuals. Participants completed performance tests at pre-, post-24 hours, and post-48 hours resistance training protocol (Baseline, Post24, and Post48). The training protocol consisted of 5 sets of 10 repetitions of back squat (BSQ) at 60% of 1 repetition maximum (1RM). SJ variables included jump height (JH), peak power (PP), and relative PP. For the IMTP and ISQ, isometric peak force (IPF), relative IPF, rate of force development at 250 milliseconds (RFD250), and impulse at 250 milliseconds (IMP250) were calculated. Significant decreases were observed from Baseline to Post24 (p = 0.023, Cohen's d z effect size [d z ] = 1.00) and Post48 (p = 0.032, d z = 0.94) in SJ JH. IMTP IMP250 significantly decreased from Baseline to Post48 (p = 0.046, d z = 0.88). Significant negative correlation was found between relative 1RM BSQ and the changes from Baseline to Post48 in ISQ RFD250 (p = 0.046,r = −0.61). Acute performance decreases might remain until 48 hours after resistance training in explosive strength and impulse regardless of isometric testing type.
... The CMJ is commonly used in professional sports to assess lower-body ballistic performance and monitor the effectiveness of training programs [11][12][13]. Many research studies confirm the high validity and reliability of the CMJ on force plates to assess motor function of the lower extremity in a variety of clinical settings [12,[14][15][16][17][18][19][20]. ...
In the early stages of multiple sclerosis (MS), there are currently no sensitive assessments to evaluate complex motor functions. The countermovement jump (CMJ), a high-challenge task in form of a maximal vertical bipedal jump, has already been investigated as a reliable assessment in healthy subjects for lower extremity motor function. The aim was to investigate whether it is possible to use CMJ to identify subthreshold motor deficits in people with multiple sclerosis (pwMS). All participants (99 pwMS and 33 healthy controls) performed three maximal CMJs on a force plate. PwMS with full motor function and healthy controls (HC) did not differ significantly in age, disease duration, Body Mass Index and the Expanded Disability Scale Score. In comparison to HC, pwMS with full motor function demonstrated a significantly decreased CMJ performance in almost all observed kinetic, temporal and performance parameters (p < 0.05). With increasing disability in pwMS, it was also observed that jump performance decreased significantly. This study showed that the CMJ, as a high challenge task, could detect motor deficits in pwMS below the clinical threshold of careful neurological examination. Longitudinal studies are pending to evaluate whether the CMJ can be used as a standardized measure of disease progression.
... Further, this division has been used to incorrectly define when the lower limb muscles are performing eccentric (downward phase) and concentric (upward phase) muscle actions. 5,6 Although this division into eccentric and concentric muscle action is supported by the vastus lateralis' fascicle length changes shown in the authors' figure 3, it has to be considered that the observed fascicle lengthening is largely passive until the above-described braking phase starts. Accordingly, an eccentric action of the vastus lateralis only occurs during the braking phase, when CoM acceleration is positive. ...
... A linear encoder tracked duration (time, in seconds) and lifting bar displacement (in meters) of all lifts (Musclelab, Ergotest; 200-Hz sampling rate and 0.019-mm resolution; used by the authors in previous publications 18,19 ). The encoder was attached to the powerlifting bar on the right-hand side (10 cm outside the knurl mark). ...
... Based on our previous work, the CVs for 1RM assessments in strength and power athletes are 3% to 5% in the squat and bench press. 18,19 Compared with the participants' personal best lifts prior to the study (during the last 3 mo), the 1RM pretests deviated by 4 (6)% and 0 (8)% (mean [SD]) for the squat and the bench press, respectively. ...
... 36 The SDs used for standardizing were confirmed as being similar to SDs from previous studies with strength-trained athletes. [18][19][20] For sRPE, PRS, and sleep magnitudes, the differences between groups were evaluated with the following scale: < 10%: trivial, 10% to 30%: small, 30% to 50%: moderate, and 50% to 80%: large. 36 To make inferences about the likelihood of the effects being significant, a 95% confidence interval (CI) was used. ...
Aims:
In the present intervention study, low-velocity-loss (LVL) versus high-velocity-loss (HVL) thresholds in the squat and bench press were compared for changes in muscle strength, power, and hypertrophy.
Methods:
Strength-trained volunteers (7♀ and 9♂; age: 27.2 [3.4] y; height: 174.6 [8.0] cm; body mass: 75.3 [10.1] kg) were randomized into an LVL or HVL threshold group (LVL n = 3♀ + 5♂, and HVL n = 4♀ + 4♂). Training took place 3 times per week over 6 weeks (loads: ∼75%-90% of 1-repetition maximum [1RM]). The thresholds of LVLs and HVLs were set at 20% and 40% of maximal velocity, respectively, for the squat, and at 30% and 60%, respectively, for the bench press. Before and after the intervention, 1RM, leg press power, and squat jump were tested. The load (∼45% of 1RM) corresponding to 1-m/s velocity was assessed in all sessions for both exercises. In addition, the thickness of the vastus lateralis and triceps brachii and body composition (dual-energy X-ray absorptiometry [DEXA]) were measured.
Results:
Squat and bench-press 1RM increased similarly in both groups by 7% to 11% (SD: 4%-6%, P < .05). No group differences were observed for changes in jump height, leg press power, or DEXA lean mass. However, HVL showed a small increase in muscle thickness of the vastus lateralis compared with LVL (6 ± 6% [95% CI] group difference, P < .05).
Conclusion:
For strength-trained individuals, high-volume lower-velocity-loss thresholds were as effective as higher thresholds for improvements in 1RM strength; but local hypertrophy was seemingly elicited faster with higher velocity-loss thresholds.
... We then conducted a multilevel mixed-effect meta-analysis using the rma.mv function in the "metafor" R package (Viechtbauer, 2010) to evaluate whether species mixing in forest plantations had significant effects on soil physicochemical properties and enzymatic activities. Treatment effects were considered significant (P < 0.05) if the 95 % CI did not overlap with zero (Hedges and Olkin, 1985;Helland et al., 2020). We assessed the heterogeneity of effect sizes using formal Cochran's Q-test to determine whether the variability of the observed effect sizes was larger than that expected by chance (Wang et al., 2020). ...
It is becoming a tendency for multispecies plantations to be promoted worldwide to enhance carbon sequestration and provide better ecosystem services. Soil physicochemical properties and enzymatic activities are critical for tree growth and biogeochemical processes. However, the effects of species mixing on soil properties and enzymatic activities in monoculture plantation forests remain unclear. We conducted a meta-analysis to quantify the effects of species mixing on soil physicochemical properties and enzymatic activities in Chinese fir plantations. We collected 4,620 paired observations from 120 studies. We found that soil physicochemical properties and enzymatic activities increased by 13.97% and 36.34% in species mixing plantations compared to monoculture plantations. Species mixing enhanced soil aeration, water holding capacity, and the total amount and availability of nutrients, increased the soil organic carbon stocks and improved soil nutrient cycling in plantations. The effects of species mixing on soil physicochemical properties and enzymatic activities were negatively correlated with slope, mean annual temperature, and mean annual precipitation but positively correlated with the number of tree species and the proportion of mixed species. In summary, our meta-analysis highlights the positive effects of species mixing on soil nutrient cycling and ecosystem function in Chinese fir plantations and recommends species mixing rather than monoculture plantations for afforestation to support the sustainable and healthy development of forests.
... A higher barbell ROM has a direct relationship with the subject's height [11,12,56,57], meaning that if the lifter is taller, the barbell needs to have a higher displacement than if the lifter is shorter. OW is a competitive sport that requires athletes to lift a maximal amount of weight in the Snatch and C&J. ...
... Recent research has also reported that different individual physical characteristics lead to different fatigue levels and recovery [57], and this could have led to greater variability in the study results. More than half of the participants showed increases in most variables instead of an expected decrease induced by fatigue. ...
... Additionally, we can speculate that some types of exercises may contribute more to the better potentiation of muscle contractions due to the lifted load, the force-velocity curve, and the different levels of induced fatigue [47,57,58,[60][61][62]. The neuromuscular adaptations induced by weightlifting training strongly depend on the manipulation of strength training variables, such as the exercise type and sequence, load magnitude, volume, interset and intraset rest periods, and lifting velocity [63,64]. ...
Load management is an extremely important subject in fatigue control and adaptation processes in almost all sports. In Olympic Weightlifting (OW), two of the load variables are intensity and volume. However, it is not known if all exercises produce fatigue of the same magnitude. Thus, this study aimed to compare the fatigue prompted by the Clean and Jerk and the Snatch and their derivative exercises among male and female participants, respectively. We resorted to an experimental quantitative design in which fatigue was induced in adult individuals with weightlifting experience of at least two years through the execution of a set of 10 of the most used lifts and derivatives in OW (Snatch, Snatch Pull, Muscle Snatch, Power Snatch, and Back Squat; Clean and Jerk, Power Clean, Clean, High Hang Clean, and Hang Power Clean). Intensity and volume between exercises were equalized (four sets of three repetitions), after which one Snatch Pull test was performed where changes in velocity, range of motion, and mean power were assessed as fatigue measures. Nine women and twelve men participated in the study (age, 29.67 ± 5.74 years and 28.17 ± 5.06 years, respectively). The main results showed higher peak velocity values for the Snatch Pull test when compared with Power Snatch (p = 0.008; ES = 0.638), Snatch (p < 0.001; ES = 0.998), Snatch Pull (p < 0.001, ES = 0.906), and Back Squat (p < 0.001; ES = 0.906) while the differences between the Snatch Pull test and the derivatives of Clean and Jerk were almost nonexistent. It is concluded that there were differences in the induction of fatigue between most of the exercises analyzed and, therefore, coaches and athletes could improve the planning of training sessions by accounting for the fatigue induced by each lift.
... A higher barbell ROM has a direct relationship with the subject's height [11,12,56,57], meaning that if the lifter is taller, the barbell needs to have a higher displacement than if the lifter is shorter. OW is a competitive sport that requires athletes to lift a maximal amount of weight in the Snatch and C&J. ...
... Recent research has also reported that different individual physical characteristics lead to different fatigue levels and recovery [57], and this could have led to greater variability in the study results. More than half of the participants showed increases in most variables instead of an expected decrease induced by fatigue. ...
... Additionally, we can speculate that some types of exercises may contribute more to the better potentiation of muscle contractions due to the lifted load, the force-velocity curve, and the different levels of induced fatigue [47,57,58,[60][61][62]. The neuromuscular adaptations induced by weightlifting training strongly depend on the manipulation of strength training variables, such as the exercise type and sequence, load magnitude, volume, interset and intraset rest periods, and lifting velocity [63,64]. ...
Load management is an extremely important subject in the control of fatigue and adaptation process in almost all sports. In Olympic Weightlifting (OW), some of the load variables are known, namely intensity and volume. However, the type of exercise remains unknown in specific terms, this is because empiricism tells us that some exercises induce greater fatigue than others, nonetheless we do not know specifically the value for this quantification. Thus, this work intends to evaluate the amount of fatigue provoke by various types of OW exercises. We resorted to an experimental quantitative design, where we induced fatigue in adult individuals with weightlifting experience of at least 2 years, through the execution of a set of 10 of the most used exercises in OW, in which the intensity and volume between them were equalized (4 sets of 3 repetitions), after which a Snatch Pull test was performed and changes in maximum and medium velocity, range of motion and medium power were evaluated as fatigue measurement, between before and after the protocol of each exercise through the linear transductor Vitruve (Vitruve encoder; Madrid, Spain). Nine women and 12 men have participated in the study (age, 29.67±5.74years and 28.17±5.06years; height, 158.78±6.70cm and 174.50±6.07cm; body weight, 60.84±7.34kg and 79.46±5.32kg; %body fat, 17.76±7.63% and 16.98±5,14%, respectively). For the total sample, significant differences were found in the range of motion (ROM) of Snatch Pull, Snatch and Back Squat (respectively, p<0.001 and ES=0.986; p=0.003 and ES=0.731 ; p=0.021 and ES=0.547) and also on C&J ROM (p=0.015 and ES=0.582), in the mean power variable, significant differences were found in Power Snatch, Snatch, Snatch Pull and Back Squat and C&J (respectively, p=0.043 and ES=0.472; p=0.048 and ES=0.460; p=0.003 and ES=0.729; p=0.009 and ES=0.636 ; p=0.037 and ES=0.488), in peak velocity, significant differences were found in Power Snatch, Snatch, Snatch Pull and Back Squat (respectively, p=0.008 and ES=0.638; p<0.001 and ES=0.998; p<0.001 and ES=0.906 ; p<0.001 and ES=0.906), in the mean velocity variable, significant differences were found in Snatch Pull and Back Squat (respectively, p=0.030 and ES=0.509; p=0.003 and ES=0.727). When genders were analyzed separately, on the female group, significant differences were noticed in Snatch ROM, Snatch Pull and Back Squat (respectively, p=0.006 and ES=1.218; p=0.001 and ES=1.776; p=0.002 and ES=1.474), in the mean power variable, significant differences were found in Snatch, Snatch Pull and Back Squat (respectively, p=0.006 and ES=1.227; p=0.002 and ES=1.512 ; p=0.001 and ES=1.679), at peak velocity significant differences were revealed in Snatch, Snatch Pull and Back Squat (respectively, p=0.002 and ES=1.469; p=0.005 and ES=1.258; p<0.001 and ES=2.058), for the mean velocity variable, significant differences were found in Snatch, Snatch pull and Back squat (respectively, p=0.006 and ES=1.228; p=0.003 and ES=1.372 ; p=0.001 and ES=1.660). In the male group, differences were found in the ROM of Snatch Pull, C&J and Clean (respectively, p=0.042 and ES=0.663; p=0.004 and ES=1.033; p=0.020 and ES=0.786) also, significant differences in mean power were only found in C&J (p=0.009 and ES=0.910, at peak velocity were revealed significant differences in Power Snatch, Snatch and Snatch Pull (respectively, p=0.009 and ES=0.910; p=0.025 and ES=0.745; p=0.039 and ES=0.675), the mean velocity showed significant differences only in the C&J (p=0.011 and ES=0.876). It is thus concluded that there are differences in the induction of fatigue between most of the exercises analyzed, and that the female gender seems to be more resistant to fatigue than the male gender, in relation to exercises derived from C&J, however in the exercises derived from snatch the reverse seems to happen in most variables except at maximum speed, in which both genders present similar fatigue in the analyzed exercises.
