High-Intensity Conditioning Activity Causes Localized Postactivation Performance Enhancement and Nonlocalized Performance Reduction.

ABSTRACT: Kolinger D, Stastny P, Pisz A, Krzysztofik M, Wilk M, Tsoukos A, and Bogdanis GC. High-intensity conditioning activity causes localized postactivation performance enhancement and nonlocalized performance reduction. J Strength Cond Res 38(1): e1-e7, 2024-This study aimed to examine whether a conditioning activity (CA) performed by the legs (barbell back squat) may cause postactivation performance enhancement (PAPE) on muscle groups other than leg extensors in isokinetic (eccentric [ECC] and concentric [CON]) and dynamic movement. Twelve male basketball players (age: 21.3 ± 3.2, body mass: 89.6 ± 14.1 kg, height: 187.4 ± 4.6 cm, and 1 repetition maximum (1RM) barbell back squat: 113 ± 21 kg) with previous resistance-training experience of at least 2 years, performed 3 sets of 3-4 repetitions of back-squats with submaximal load (60, 90, and 90% 1RM) as CA. Before and after the CA, they performed pretest and post-test in the form of countermovement jumps (CMJs) (localized) or explosive push-ups (EPUs) (nonlocalized) along with isokinetic flexion and extension at the knee (localized) or at the elbow (nonlocalized). The localized and nonlocalized protocols were divided into 2 days in a randomized order. The back squat as CA significantly increased peak torque (PT) (p < 0.05) in all CON and ECC muscle actions and average power per repetition (APPR) (p < 0.05) (all muscle actions except ECC flexion) of the localized isokinetic tests with large (>0.8) and medium (0.4-0.79) effect sizes and significantly decreased (p < 0.01) the PT and APPR (p < 0.01) of the nonlocalized isokinetic test in the ECC flexion. The CMJ and EPU tests showed no significant differences (p > 0.05) between premeasures and postmeasures of take-off height. The effect of PAPE seems to be specific to the muscles most involved in the CA, and the CA inhibits PT of subsequent muscle ECC contractions in muscles not involved in the CA.

The Ratio between Weekly Training and Match External Physical Loads in U17 Elite Youth Soccer Players: Implications for the Training Process.

Research on the external physical load on elite youth soccer players during the weekly training microcycle in competitive periods and official matches is limited. The aims of this study were twofold: a) investigate possible differences in external physical load (PL) across player positions in U17 elite youth soccer players during official matches; b) determine the weekly training to match physical load ratio (WTMLr) across player positions. The sample included 20 outfield players from an elite soccer academy (mean age 15.94 ± 0.25 years) playing in four positions: central defender (CD), full-back (FB), central midfielder (CM) and Striker (S). Data were collected during the spring in-season period for 17 official matches played in a 4-3-3 game format. Indicators of external physical load monitored were: total distance (TD); total distance in high-speed running (HSR; > 16.1 km.h-1); total distance in sprint running (SPR; > 21.6 km.h-1); and relative physical load intensity (%HSR). The WTMLr was calculated for TD, HSR, SPR and %HSR as the ratio of the average weekly sum of training PL to the average sum of PL in an official match for a given players' position. Collectively, the training intensity during a one-week microcycle (%HSR in WTMLr) achieved only 76 % of match demands. CD performed significantly lower in all measured indicators of external PL during the official match than all other positions (p < 0.05; g > 0.80) except for TD in S. S achieved significantly higher SPR during official matches compared to CD (p < 0.05; g > 0.80), CM, and FB (g > 0.80). In contrast, CD reported higher WTMLr (medium-large effect size) in HSR and SPR indicators than all other positions. CM performed significantly higher %HSR in WTMLr than S and FB (p < 0.05; g > 0.80). Results revealed insufficient training intensity relative to match demands and, at the same time, weekly training PL did not meet match demands (especially in HSR and SPR) for players across the different positions. Therefore, practitioners should select appropriate training methods (drills and games) to ensure sufficient training intensity (HSR and SR metrics) and consider using the WTMLr, which can be used to help optimise and individualise training PL for different player positions.

Acute Effects of Varied Back Squat Activation Protocols on Muscle-Tendon Stiffness and Jumping Performance.

ABSTRACT: Krzysztofik, M, Wilk, M, Pisz, A, Kolinger, D, Tsoukos, A, Zajac, A, Stastny, P, and Bogdanis, GC. Acute effects of varied back squat activation protocols on muscle-tendon stiffness and jumping performance. J Strength Cond Res 37(7): 1419-1427, 2023-Intensity, movement velocity, and volume are the principal factors to successfully use postactivation performance enhancement. Therefore, 15 resistance-trained volleyball players completed 3 different back squat configurations as a conditioning activity (CA) in randomized order: (a) 3 sets of 3 repetitions at 85% 1RM (HL); (b) a single set of back squats at 60% 1RM until 10% mean velocity loss (VB); (c) and 2 sets of back squats at 60% 1RM until 10% mean velocity loss (2VB) on subsequent countermovement jump performance, Achilles tendon, and vastus lateralis stiffness with concomitant front thigh skin surface temperature assessment. The measurements were performed 5 minutes before the CA and at 2, 4, 6, 8, and 10 minutes. The jump height was significantly increased in the second minute and at peak, post-CA compared with baseline for all conditions ( p = 0.049; ES = 0.23 and p < 0.001; ES = 0.37). Skin surface temperature was significantly increased for all post-CA time points compared with baseline in the 2VB condition ( p from <0.001-0.023; ES = 0.39-1.04) and in the fourth minute and at peak post-CA in HL condition ( p = 0.023; ES = 0.69 and p = 0.04; ES = 0.46), whereas for the VB condition, a significant decrease in peak post-CA was found ( p = 0.004; ES = -0.54). Achilles tendon stiffness was significantly decreased for second, fourth, eighth, 10th, and peak post-CA in comparison to baseline for all conditions ( p from p = 0.004-0.038; ES = -0.47 to -0.69). Vastus lateralis stiffness was significantly decreased for peak post-CA compared with baseline for all conditions ( p = 0.017; ES = -0.42). We recommend using a single set of barbell squats with a 10% velocity loss as a mechanism of fatigue control to acutely improve jump height performance and avoid unnecessary increases in training volume.

Acute Effects of Isometric Conditioning Activity on the Viscoelastic Properties of Muscles and Sprint and Jumping Performance in Handball Players.

ABSTRACT: Krzysztofik, M, Spieszny, M, Trybulski, R, Wilk, M, Pisz, A, Kolinger, D, Filip-Stachnik, A, and Stastny, P. Acute effects of isometric conditioning activity on the viscoelastic properties of muscles and sprint and jumping performance in handball players. J Strength Cond Res 37(7): 1486-1494, 2023-The effects of conditioning activity (CA) on muscle stiffness are currently unknown, suggesting that maximum CA effort can increase or decrease the stiffness of involved muscle groups. Therefore, this study aimed to investigate the effect of maximal isometric half-squats on the viscoelastic properties of muscles and postactivation performance enhancement (PAPE) in sprints and jumps. Twelve handball players underwent a standard warm-up and baseline assessment of muscle stiffness and tone of vastus lateralis and gastrocnemius medialis muscle, followed by 20-m sprint with intermediate measures at 5 and 10 m and countermovement jump. The PAPE was assessed by repeating the tests (at 4th, 8th, and 12th minute post-CA) after a CA protocol consisting of 3 sets of 3-second maximal isometric half-squats (EXP) or a control condition (CTRL) without any CA. The vastus lateralis stiffness in the 4th and 12th minute and muscle tone in the 4th minute post-CA significantly decreased compared with baseline ( p = 0.041, ES = 0.57; p = 0.013, ES = 0.52; p = 0.004, ES = 0.81, respectively) in the EXP condition. The 20-m sprint time significantly decreased at all post-CA time points compared with the baseline for the EXP condition ( p < 0.033) and the after values in the CTRL condition ( p < 0.036). In comparison to baseline, the 10-m sprint time decreased in the eighth minute post-CA ( p = 0.021; ES = 0.82) in the EXP condition. Moreover, it was significantly lower at the 8th and 12th minute post-CA ( p = 0.038; ES = 0.71 and p = 0.005; ES = 1.26) compared with that time points in the CTRL condition. The maximal isometric half-squats effectively improved sprint performance and significantly decreased vastus lateralis tone and stiffness. These findings offer new insights into the assessment of viscoelastic properties for evaluating the fatigue or potentiation state, which requires further investigation.

Acute Effects of High-Load vs. Plyometric Conditioning Activity on Jumping Performance and the Muscle-Tendon Mechanical Properties.

ABSTRACT: Krzysztofik, M, Wilk, M, Pisz, A, Kolinger, D, Bichowska, M, Zajac, A, and Stastny, P. Acute effects of high-load versus plyometric conditioning activity on jumping performance and the muscle-tendon mechanical properties. J Strength Cond Res 37(7): 1397-1403, 2023-The effectiveness of high-load and plyometric exercises as conditioning activity (CA) is not well described in the level of performance enhancement and muscle-tendon properties. Therefore, this study aimed to compare the effectiveness of high-loaded back squats and body mass tuck jumps among amateur soccer players on the height of countermovement jump performed without (CMJ) and with arm swing (CMJa) and to verify the usefulness of the myotonometry in assessing the level of CA-induced fatigue. Therefore, 16 male amateur soccer players (resistance training experience: 2 ± 1 year, relative 1 repetition maximum back squat strength: 1.41 ± 0.12 kg·body mass-1) performed 3 experimental sessions to compare the acute effects of 3 sets of 3 repetitions at 85% one repetition maximum of half back squats (HL), 3 sets of 5 repetitions of tuck jump exercises (PLY), and no CA (CTRL) on CMJ and CMJa height. Moreover, the gastrocnemius medialis and Achilles tendon tone and stiffness were examined. Measurements were performed 5 minutes before CA and in the third, sixth, and ninth minutes after CA. The CMJ height significantly increased from pre-CA to post-CA in the CTRL (p = 0.005; effect size [ES] = 0.36; Δ = +3.4%) and PLY (p = 0.001; ES = 0.83; Δ = +8.8%) conditions. Moreover, post-CA jump height was significantly higher in PLY than in the HL condition (p = 0.024; ES = 0.6; Δ = +5.9%). No significant differences were found for CMJa height, tone, and stiffness of gastrocnemius medialis and Achilles tendon. The low-volume plyometric CA (i.e., 3 sets of 5 repetitions) is recommended instead of high-loaded CA (≥85% one repetition maximum) for amateur athletes. In addition, it has been established that the performance improvement was independent of changes in the mechanical properties of the gastrocnemius medialis and Achilles tendon. Furthermore, it seems that the complexity of the post-CA task may affect the magnitude of the postactivation performance enhancement.

Testing distance characteristics and reference values for ice-hockey straight sprint speed and acceleration. A systematic review and meta-analyses.

Ice-hockey requires high acceleration and speed sprint abilities, but it is unclear what the distance characteristic is for measuring these capabilities. Therefore, this systematic meta-analysis aims to summarize the sprint reference values for different sprint distances and suggest the appropriate use of ice-hockey straight sprint testing protocols. A total of 60 studies with a pooled sample of 2254 males and 398 females aged 11-37 years were included. However, the pooled data for women was not large enough to permit statistical analysis. The sprint distance used for measuring the reported acceleration and speed was between 4-48 m. Increased test distance was positively associated with increased speed (r = 0.70) and negatively with average acceleration (r = -0.87). Forward skating sprint speed increases with the measured distance up to 26 m and do not differ much from longer distance tests, while acceleration decreases with a drop below 3 m/s at distances 15 m and longer. The highest acceleration (5.89 m/s2 peak, 3.31 m/s2 average) was achieved in the shortest distances up to 7 m which significantly differs from 8-14 m tests. The highest speed (8.1 m/s peak, 6.76 m/s average) has been recorded between 26-39 m; therefore, distances over 39 m are not necessary to achieve maximum speed. Considering match demands and most reported test distances, 6.1 m is the recommended distance for peak acceleration and 30 m for peak speed. The sprint time, acceleration, and speed of each individual and the number of skating strides should be reported in future studies.

Elite young soccer players have smaller inter-limb asymmetry and better body composition than non-elite players.

Body composition (BC) and inter-limb anthropometric asymmetries (LA) may influence the physical performance of soccer players. This study aimed to determine differences in BC and LA among soccer across four performance levels. The study involved 110 male soccer players participating in Czech senior teams who were grouped into four different performance levels (i.e. G1: national team, G2: 1st division, G3: 2nd division, G4: 3rd division). The following BC and LA parameters were compared among groups: body height, body mass, absolute fat-free mass, relative fat-free mass (FFMrel), percentage of fat mass (FM), total body water (TBW), intracellular water (ICW), extracellular water (ECW), phase angle, and bilateral muscle mass differences in the upper and lower extremities. Significant differences were observed in BC parameters among all groups (λ = 0.06, F75,246 = 5.38, p = 0.01, ηp 2 = 0.62). High-performance players (i.e. G1, G2) had significantly (p < 0.01) lower FM than lower performance players (i.e. G3, G4). The lowest values of FFMrel, relative TBW, relative ICW and ECW were detected in the lowest-performance players (i.e. G4). Significantly lower bilateral muscle mass differences were detected in G1 players (2.71 ± 1.26%; p < 0.01) compared with G4 players (3.95 ± 1.17%). G1 and G2 players had a higher proportion of muscle mass in the torso (p < 0.01) and upper limbs than G3 and G4 (p < 0.01). Elite and high-performance players have better BC and lower inter-limb anthropometric asymmetries compared with low-performance level players.

Do physical activity interventions combining self-monitoring with other components provide an additional benefit compared with self-monitoring alone? A systematic review and meta-analysis.

OBJECTIVE: To determine the net effect of different physical activity intervention components on step counts in addition to self-monitoring. DESIGN: A systematic review with meta-analysis and meta-regression. DATA SOURCES: Five databases (PubMed, Scopus, Web of Science, ProQuest and Discus) were searched from inception to May 2022. The database search was complemented with backward and forward citation searches and search of the references from relevant systematic reviews. ELIGIBILITY CRITERIA: Randomised controlled trials comparing an intervention using self-monitoring (active control arm) with an intervention comprising the same treatment PLUS any additional component (intervention arm). DATA EXTRACTION AND SYNTHESIS: The effect measures were mean differences in daily step count. Meta-analyses were performed using random-effects models, and effect moderators were explored using univariate and multivariate meta-regression models. RESULTS: Eighty-five studies with 12 057 participants were identified, with 75 studies included in the meta-analysis at postintervention and 24 at follow-up. At postintervention, the mean difference between the intervention and active control arms was 926 steps/day (95% CI 651 to 1201). At a follow-up, the mean difference was 413 steps/day (95% CI 210 to 615). Interventions with a prescribed goal and involving human counselling, particularly via phone/video calls, were associated with a greater mean difference in the daily step count than interventions with added print materials, websites, smartphone apps or incentives. CONCLUSION: Physical activity interventions that combine self-monitoring with other components provide an additional modest yet sustained increase in step count compared with self-monitoring alone. Some forms of counselling, particularly remote phone/video counselling, outperformed other intervention components, such as websites and smartphone apps. PROSPERO REGISTERED NUMBER: CRD42020199482.

Assisted Jumping in Healthy Older Adults: Optimizing High-Velocity Training Prescription.

ABSTRACT: Tufano, JJ, Vetrovsky, T, Stastny, P, Steffl, M, Malecek, J, and Omcirk, D. Assisted jumping in healthy older adults: optimizing high-velocity training prescription. J Strength Cond Res 36(6): 1518-1523, 2022-Because older adults benefit from power training, training strategies for athletes such as supramaximal velocity-assisted jumping could also be useful for older adults. However, optimizing-assisted exercise prescription in older adults remains uninvestigated. Therefore, the purpose of this study was to determine the effects of different bodyweight (BW) assistance levels on jumping force and velocity in healthy older adults. Twenty-three healthy older adults (67.6 ± 7.6 years, 167.0 ± 8.8 cm, 72.7 ± 14.3 kg, and 27.1 ± 6.9% body fat) performed 5 individual countermovement jumps at BW, 90, 80, 70, and 60% of BW. Jumps were performed on a force plate, which provided peak take-off force (TOF), flight time, and peak impact force. A linear position transducer measured peak concentric velocity (PV). The rating of perceived exertion (RPE) was also assessed after each condition. Take-off force was greater during BW than all other conditions, 90 and 80% were greater than 70 and 60%, but there were no differences between 80 and 90% or between 70 and 60%. The FT progressively increased at all assistance levels, and PV was faster for all assistance levels than BW, with no differences between assistance levels. Impact force was greater during BW than 80, 70, and 60% and was greater during 90% than 60%. The RPE was less than BW during all assistance conditions but was the least during 70%. Implementing assisted jumping between 70 and 80% of BW in older adults likely provides the ideal combination of force, velocity, and RPE.

Does a linear position transducer placed on a stick and belt provide sufficient validity and reliability of countermovement jump performance outcomes?

Manufacturers recommend that linear position transducers (LPTs) should be placed on the side of a barbell (or wooden dowel) to measure countermovement jump (CMJ) height, but the validity and reliability of this placement have not been compared to other attachment sites. Since this recommended attachment site is far from the centre of mass, a belt attachment where the LPT is placed between the feet may increase the validity and reliability of CMJ data. Thirty-six physical education students participated in the study (24.6 ± 4.3 years; 177.0 ± 7.7 cm; 77.2 ± 9.0 kg). Parameters from the two LPT attachments (barbell and belt) were simultaneously validated to force plate data, where the nature of bias was analysed (systematic vs random). The within-session and between-session reliability of both attachment sites were compared to force plate data using a test-retest protocol of two sets of 5 CMJs separated by 7 days. The LPT provided highly reliable and valid measures of peak force, mean force, mean power, and jump height, where the bias was mostly systematic (r2 > 0.7; ICC > 0.9). Peak velocity, mean velocity, and peak power were in very good agreement with the force plate and were highly reliable (r2 > 0.5; ICC > 0.7). Therefore, both attachment sites produced similar results with a systematic bias compared to force plate data. Thus, both attachment sites seem to be valid for assessing CMJs when the measuring tool and site remain consistent across measurements. However, if LPT data are to be compared to force plate data, recalculation equations should be used.

Speed and power-related gene polymorphisms associated with playing position in elite soccer players.

Heritability studies on sport-related traits accepted that endurance, speed, power, and strength abilities include an active genetic predisposition to elite soccer participation. This study evaluates the influence of selected genetic variants on performance in speed, power, and strength laboratory tests on a group of elite soccer players, including their playing position. A ninety-nine male elite soccer players were compared to controls (n = 107) and tested for quadriceps and hamstrings isokinetic strength at speed 60°/s, 180°/s, and 300°/s, jump performance, and genotypes of ACTN3 (R577X, rs1815739), ACE (I/D, rs1799752), NOS3 (Glu298Asp, rs1799983), AMPD1 (34C/T, rs17602729), UCP2 (Ala55Val, rs660339), BDKRB2 (+9/-9, rs5810761) and IL1RN (VNTR 86-bp). The ACTN3 XX homozygotes in defenders had lower quadriceps and hamstring isokinetic strength in all tested speeds than ACTN3 RX and RR genotypes (p < 0.05). The ACTN3 RR homozygotes in defenders had higher quadriceps strength in all tested velocities than the RX heterozygotes (p < 0.05). We also found other associations between playing-position in soccer and increased strength of lower limbs for AMPD1 CC and NOS3 Glu/Glu genotypes, and IL1RN*2 allele carriers. Total genetic score regression explained 26% of the variance in jump performance and isokinetic strength. The ACTN3 R allele, NOS3 Glu/Glu genotypes, and IL1RN*2 allele pre-disposed the attackers and defenders playing position in elite soccer, where those positions have higher strength and power measures than midfielders. Midfielders have lower strength and power conditions than other playing positions without relation to strength and power genes.

Effects of Unilateral Conditioning Activity on Acute Performance Enhancement: A Systematic Review.

This review aimed to summarize the reported effects of unilateral conditioning activity (CA) on unilateral performance, bilateral performance, and the contribution of activated body limb to bilateral performance. A systematic search on MEDLINE, SPORTDiscus, Scopus, and Google Scholar was conducted on February 2022. Twenty-three studies met the inclusion criteria. Throwing, jumping, swimming, change of direction, and isokinetic performance were used as outcome measures to assess the impact of unilateral CAs on inducing post-activation performance enhancement. Eleven studies examined the effectiveness of resistance exercises as a CA, seven investigated plyometric exercises, and five used isokinetic muscle actions as CAs. Notably, only three studies directly compared the effects of bilateral and unilateral CA, and no study reported possible changes in the contribution of each limb during bilateral exercises executed following unilateral CA. Split squats were the most often studied CA (7), and it was shown that multiple sets of high-loaded split squats (85% one-repetition maximum) executed as CA, improve vertical jumping and change of direction after 4 to 8 min of recovery. At the same time, multiple sets of alternate leg bounds performed with ~10% body weight or without any external load result in an improvement of sprint performance, 2 and 8 min later, with the effect being greater when loaded jumps are used. The unilateral CAs such as split squats, alternate leg bounds, and drop jumps can be effectively used to acutely improve a wide variety of athletic tasks, including jumping, sprinting, change of direction, and swimming performance.

Morning fatigue and structured exercise interact to affect non-exercise physical activity of fit and healthy older adults.

BACKGROUND: Exercise training is crucial for maintaining physical and mental health in aging populations. However, as people participate in structured exercise training, they tend to behaviorally compensate by decreasing their non-exercise physical activity, thus potentially blunting the benefits of the training program. Furthermore, physical activity of older adults is substantially influenced by physical feelings such as fatigue. Nevertheless, how older people react to day-to-day fluctuations of fatigue and whether fatigue plays a role in non-exercise physical activity compensation is not known. Thus, the purpose of this study was twofold: (1) To explore whether the volume and intensity of habitual physical activity in older adults were affected by morning fatigue. (2) To investigate the effect of attending power and resistance exercise sessions on the levels of non-exercise physical activity later that day and the following day. METHODS: Twenty-eight older adults wore an accelerometer during a 4-week low-volume, low-intensity resistance and power training program with three exercise sessions per week and for 3 weeks preceding and 1 week following the program. During the same period, the participants were prompted every morning, using text messages, to rate their momentary fatigue on a scale from 0 to 10. RESULTS: Greater morning fatigue was associated with lower volume (p = 0.002) and intensity (p = 0.017) of daily physical activity. Specifically, one point greater on the fatigue scale was associated with 3.2 min (SE 1.0) less moderate-to-vigorous physical activity. Furthermore, attending an exercise session was associated with less moderate-to-vigorous physical activity later that day by 3.7 min (SE 1.9, p = 0.049) compared to days without an exercise session. During the next day, the volume of physical activity was greater, but only in participants with a body mass index up to 23 (p = 0.008). CONCLUSIONS: Following low-volume exercise sessions, fit and healthy older adults decreased their non-exercise physical activity later that day, but this compensation did not carry over into the next day. As momentary morning fatigue negatively affects daily physical activity, we suggest that the state level of fatigue should be monitored during intensive exercise programs, especially in less fit older adults with increased fatigability.

Overspeed Stimulus Provided by Assisted Jumping Encourages Rapid Increases in Strength and Power Performance of Older Adults.

Following a 4-week control period, 24 older men and women (55-91 years) attended a 4-week progressive jumping program to determine whether assisted jumping could be safely and effectively implemented as a novel stimulus in healthy older adults. Bodyweight countermovement jump performance, isometric and isokinetic strength, postural stability, and exercise enjoyment were assessed before the control period, before the training intervention, and after the training intervention. Following the 4-week intervention, eccentric quadriceps strength increased by 19 N·m (95% confidence interval [2, 36], p = .013), bodyweight countermovement jump height increased by 1.7 cm (95% CI [0.5, 2.9], p < .001), postural sway improved by 2.1 mm/s (95% CI [0.3, 4.0], p = .026), and the participants' perceived exercise enjoyment improved (p = .026). Therefore, using assisted jumping to induce an overspeed training stimulus in a jump training program resulted in similar performance improvements as in previous studies in older populations but with less training volume and a shorter training duration.

The effect of breathing technique on sticking region during maximal bench press.

The intrathoracic pressure and breathing strategy on bench press (BP) performance is highly discussed in strength competition practice. Therefore, the purpose of this study was to analyze whether different breathing techniques can influence the time and track characteristics of the sticking region (SR) during the 1RM BP exercise. 24 healthy, male adults (age 23 ± 2.4 yrs., body mass 85 ± 9.2 kg, height 181 ± 5.4 cm) performed a 1 repetition BP using the breathing technique of Valsalva maneuver (VM), hold breath, lung packing (PAC), and reverse breathing (REVB), while maximum lifted load and concentric phase kinematics were recorded. The results of ANOVA showed that the REVB breathing decreased absolute (p < 0.04) and relative lifted load (p < 0.01). The VM showed lower (p = 0.01) concentric time of the lift than the other breathing techniques. The VM and PAC showed lower SR time than other breathing techniques, where PAC showed a lower SR time than VM (p = 0.02). The PAC techniques resulted in shorter SR and pre-SR track than other breathing techniques and the REVB showed longer SR track than the other considered breathing techniques (p = 0.04). Thus, PAC or VM should be used for 1RM BP lifting according to preferences, experiences and lifting comfort of an athlete. The hold breath technique does not seem to excessively decrease the lifting load, but this method will increase the lifting time and the time spend in the sticking region, therefore its use does not provide any lifting benefit. The authors suggest that the REVB should not be used during 1 RM lifts.

Acute impact of blood flow restriction on strength-endurance performance during the bench press exercise.

The main goal of the present study was to evaluate the acute effects of blood flow restriction (BFR) at 70% of full arterial occlusion pressure on strength-endurance performance during the bench press exercise. The study included 14 strength-trained male subjects (age = 25.6 ± 4.1 years; body mass = 81.7 ± 10.8 kg; bench press 1 repetition maximum (1RM) = 130.0 ± 22.1 kg), experienced in resistance training (3.9 ± 2.4 years). During the experimental sessions in a randomized crossover design, the subjects performed three sets of the bench press at 80% 1RM performed to failure with two different conditions: without BFR (CON); and with BFR (BFR). Friedman's test showed significant differences between BFR and CON conditions for the number of repetitions performed (p < 0.001); for peak bar velocity (p < 0.001) and for mean bar velocity (p < 0.001). The pairwise comparisons showed a significant decrease for peak bar velocity and mean bar velocity in individual Set 1 for BFR when compared to CON conditions (p = 0.01 for both). The two-way repeated measures ANOVA showed a significant main effect for the time under tension (p = 0.02). A post-hoc comparisons for the main effect showed a significant increase in time under tension for BFR when compared to CON (p = 0.02). The results of the presented study indicate that BFR used during strength-endurance exercise generally does not decrease the level of endurance performance, while it causes a drop in bar velocity.

The effects of resistance training experience on movement characteristics in the bench press exercise.

The main aim of this study was to determine whether the level of experience in strength training has a significant effect on differences in the value of exercise volume determined on time under tension (TUT) and number of repetition (REP) for a specific movement tempo. The study examined 68 men divided into groups of beginners and advanced strength trained athletes. The participants performed 5 sets of bench press (BP) at 70% 1RM using either a REG, MED or SLOW metronome guided cadence. Each set was performed to failure and with 3 min of rest between sets. Significant differences in TUT were found between the groups of beginners and advanced athletes for the slow (SLO) 6/0/4/0 tempo in set 1 (p = 0.01) and set 2 (p = 0.04), and for the regular (REG) 2/0/2/0 tempo in set 5 (p = 0.01). Significant differences were documented for total TUT between the beginners and advanced athletes for the SLO 6/0/4/0 tempo (p = 0.04). The results of ANOVA revealed significant differences in the number of repetitions between groups for the SLO 6/0/4/0 tempo in set 4 (p = 0.04) and set 5 (p = 0.04), and for the REG 2/0/2/0 tempo in set 5 (p = 0.01). The main finding of this study is that strength training experience has a significant effect on training volume, both in terms of TUT and REP at a specific constant movement tempo. Significant differences do not occur for each value of the tempo used.

Association of Elite Sports Status with Gene Variants of Peroxisome Proliferator Activated Receptors and Their Transcriptional Coactivator.

BACKGROUND: Although the scientific literature regarding sports genomics has grown during the last decade, some genes, such as peroxisome proliferator activated receptors (PPARs), have not been fully described in terms of their role in achieving extraordinary sports performance. Therefore, the purpose of this systematic review was to determine which elite sports performance constraints are positively influenced by PPARs and their coactivators. METHODS: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were used, with a combination of PPAR and sports keywords. RESULTS: In total, 27 studies that referred to PPARs in elite athletes were included, where the Ala allele in PPARG rs1801282 was associated with strength and power elite athlete status in comparison to subelite athlete status. The C allele in PPARA rs4253778 was associated with soccer, and the G allele PPARA rs4253778 was associated with endurance elite athlete status. Other elite status endurance alleles were the Gly allele in PPARGC1A rs8192678 and the C allele PPARD rs2016520. CONCLUSIONS: PPARs can be used for estimating the potential to achieve elite status in human physical performance in strength and power, team, and aerobic sports disciplines. Carrying specific PPAR alleles can provide a partial benefit to achieving elite sports status, but does not preclude achieving elite status if they are absent.

Effect of COL5A1, GDF5, and PPARA Genes on a Movement Screen and Neuromuscular Performance in Adolescent Team Sport Athletes.

Stastny, P, Lehnert, M, De Ste Croix, M, Petr, M, Svoboda, Z, Maixnerova, E, Varekova, R, Botek, M, Petrek, M, Lenka, K, and Cieszczyk, P. Effect of COL5A1, GDF5, and PPARA genes on a movement screen and neuromuscular performance in adolescent team sport athletes. J Strength Cond Res 33(8): 2057-2065, 2019-The risk of injury increases with adolescents' chronological age and may be related to limited muscle function neuromuscular, genetic, and biomechanical factors. The purpose of this study was to determine whether COL5A1, PPARA, and GDF5 genes are associated with muscle functions and stretch-shortening cycle performance in adolescent athletes. One hundred forty-six youth players (14.4 ± 0.2 years) from various team sports (basketball n = 54, soccer n = 50, handball n = 32) underwent a manual test for muscle function, maturity estimation, functional bend test (FBT), passive straight leg raise (SLR) test, leg stiffness test, test of reactive strength index (RSI), and gene sampling for COL5A1, PPARA, and GDF5. The χ test did not show any differences in allele or genotype frequency between participants before and after peak height velocity. Multivariate analysis of variance showed that COL5A1 rs12722 CT heterozygotes had worse score in FBT (p < 0.001), worse score in SLR (p = 0.003), and lower maturity offset (p = 0.029, only in females) than TT homozygotes. Male GDF5 rs143383 GG homozygotes showed better score in SLR than AA and AG genotypes (p = 0.003), and AA and AG genotypes in both sex had greater RSI than GG homozygotes (p = 0.016). The PPARA rs4253778 CC homozygotes had greater RSI than GG and GC genotypes (p = 0.004). The CT genotype in COL5A1 rs12722 is possible predictor of functional movement disruption in the posterior hip muscle chain, causing shortening in FBT and SLR, which includes hamstrings function. CT genotype in COL5A1 rs12722 should be involved in programs targeting hamstring and posterior hip muscle chain.

Systematic review of intra-abdominal and intrathoracic pressures initiated by the Valsalva manoeuvre during high-intensity resistance exercises.

The Valsalva manoeuvre, intra-abdominal pressure (IAP) and intrathoracic pressure (ITP) play important roles in resistance training and common daily activities. The purpose of this review is to summarize the ITP and IAP responses to resistance exercises and to determine which exercises elicit the highest or lowest body pressure values under high-intensity resistance exercise. The PubMed, Scopus and Web of Science databases were searched until November 1, 2018. A combination of the following search terms was used: Valsalva manoeuvre, hold breath, controlled breathing, controlled breath, abdominal pressure, intrathoracic pressure AND weight training, resistance exercise, power lifting. The search process yielded 1125 studies, of which 16 were accepted according to the selection criteria and methodological quality. The highest IAP was recorded during squats (over 200 mmHg) followed by deadlift, slide row and leg press (161-176 mmHg), and the lowest IAP was found during bench press (79±44 mmHg). The highest ITP was elicited by the leg press, deadlift and box lift (105-130 mmHg), which were higher than during the bench press (95±37 mmHg) and slide row (88±32 mmHg). We recommend the bench press and slide row as exercises useful for beginners and individuals with hypertension. Untrained individuals should not use heavy squats, deadlift, box lift and clean exercises until they have undergone progressive adaptation for lifting high loads resulting in high IAP and ITP. The values of IAP and ITP during high-intensity exercise seem to be determined mutually by the position of the human body and the external load.