Half Squat Research Articles

Frequency of Interruptions to Sitting Time: Benefits for Postprandial Metabolism in Type 2 Diabetes.

To determine whether interrupting sitting with brief bouts of simple resistance activities (SRAs) at different frequencies improves postprandial glucose, insulin, and triglycerides in adults with medication-controlled type 2 diabetes (T2D). Participants (n = 23, 10 of whom were female, with mean ± SD age 62 ± 8 years and BMI 32.7 ± 3.5 kg · m-2) completed a three-armed randomized crossover trial (6- to 14-day washout): sitting uninterrupted for 7 h (SIT), sitting with 3-min SRAs (half squats, calf raises, gluteal contractions, and knee raises) every 30 min (SRA3), and sitting with 6-min SRAs every 60 min (SRA6). Net incremental areas under the curve (iAUCnet) for glucose, insulin, and triglycerides were compared between conditions. Glucose and insulin 7-h iAUCnet were attenuated significantly during SRA6 (glucose 17.0 mmol · h · L-1, 95% CI 12.5, 21.4; insulin 1,229 pmol · h · L-1, 95% CI 982, 1,538) in comparison with SIT (glucose 21.4 mmol · h · L-1, 95% CI 16.9, 25.8; insulin 1,411 pmol · h · L-1, 95% CI 1,128, 1,767; P < 0.05) and in comparison with SRA3 (for glucose only) (22.1 mmol · h · L-1, 95% CI 17.7, 26.6; P = 0.01) No significant differences in glucose or insulin iAUCnet were observed in comparison of SRA3 and SIT. There was no statistically significant effect of condition on triglyceride iAUCnet. In adults with medication-controlled T2D, interrupting prolonged sitting with 6-min SRAs every 60 min reduced postprandial glucose and insulin responses. Other frequencies of interruptions and potential longer-term benefits require examination to clarify clinical relevance.

DOUBLE LEG SPEED HOP AND HALF SQUAT JUMP IMPROVE LEG MUSCLE POWER

Leg muscle explosiveness is one of the factors that determine the stability of jumping techniques in football. This research aims to prove that the combined training of Double Leg Speed ??Hop and Half Squat Jump is better than the Hurdle Jump in increasing leg muscle explosive power in male students participating in extracurricular football at SMP Negeri 2 Kuta Utara. Type of this research was true experimental with randomized pre and post-test with control group design. The research subjects were 18 male extracurricular football students at SMP Negeri 2 Kuta Utara which were divided into two different treatment groups. Treatment group was given training in a combination of Double Leg Speed ??Hop and Half Squat Jump and control group was given hurdles training, with a frequency of training 3 times a week for 6 weeks. Measurement of leg muscle strength measured using a meter board with a vertical jump test. The results of the study in both groups obtained the average leg muscle explosive power before training in the combination of Double Leg Speed ??Hop and Half Squat Jump 38.49 ± 4.658 cm, while after training the combination of Double Leg Speed ??Hop and Half Squat Jump became 48.17 ± 4.305 cm. The average explosive power of leg muscles before the Skipping Jump training was 36.63 ± 3.953 cm, while after the skipping jump training was 40.79 ± 4.227 cm. The mean difference test in the increased leg muscle power in treatment group and control group using independent t-tests in the post-test data of the two groups showed that p = 0.00 (p &lt;0.05). It was concluded that the exercises in Treatment Group and Control Group both had an increased effect and in Treatment Group increased leg muscle power more than in Control Group. This research suggestions are expected to coaches can provide training properly and use evaluation monitoring improves athlete achievement.&#x0D; Keywords: Leg Muscle Explosive Power; Double Leg Speed ??Hop; Half Squat Jump; Hurdles Jumping; Football Extracurricular Boys SMP N 2 Kuta Utara

Relative Contribution among Physical Fitness Factors Contributing to the Performance of Modern Pentathlon.

This study reveals the relationship between physical fitness factors and performance in modern pentathlon and identifies the contribution of each physical factor to overall performance. The physical fitness assessment data and the competition records collected by the Korean national team pentathletes for the years 2005 to 2019 were tracked. The correlation between the competition records and fitness factors was confirmed by correlation analysis. In addition, the physical factors affecting performance were identified through multiple regression analysis, and the average difference between national and international competitions was verified by t-test. The first result was that fencing, swimming, and horseback riding rankings were more relevant to the overall pentathlon performance score than the combined rankings in national competitions. In the international competitions, performance in the combined running and shooting event was more relevant than fencing, swimming, and horseback riding. Second, the basic fitness factors of grip strength and sergeant jump and the specific fitness factors of leg strength—left and right average flexor were correlated with overall pentathlon performance national competitions. However, in international competitions, sergeant jump, 20 m shuttle run, reaction time, lung capacity, and back strength were correlated (presented in high to low order). In terms of the specific fitness factors, relative (%BW) and absolute (Nm) leg strength—left and right average flexor, lower body anaerobic fatigue rate, half squat, relative (W/kg) and absolute (Watts) maximal lower body anaerobic power were correlated accordingly with overall pentathlon performance. Third, we analyzed the differences between average performance in national and international competitions. Only the combined running and shooting event out of the five modern pentathlon events showed a difference. Grip strength and relative leg strength—average extensor AP (%BW) appeared to be different among the physical fitness factors. Fourth, we examined the level of contribution of each of the fitness factors on overall performance. The model’s goodness of fit was confirmed, and grip strength was found to have a significant contribution on overall performance. Furthermore, the level of contribution was higher in the following order: relative leg strength—left and right average flexor (%BW), bench press, half squat, relative leg strength—average extensor AP(%BW), GXT—time to exhaustion, relative lower body anaerobic average power (W/kg), and maximal lactic acid concentration. With the 2020 Tokyo Olympics just around the corner, combined running and shooting performance appeared to be a decisive factor in the final ranking in modern pentathlon according to the analysis of the basic and specific fitness factors of pentathletes. The basic fitness factors are critical in order of sergeant jump, grip strength, reaction time, lung capacity, side-step, back strength, 20 m shuttle run, sit-and-reach, sit-ups, and single leg standing. With respect to the specific fitness factors, relative leg strength—left and right average flexor (%BW), bench press, half squat, relative leg strength—average extensor AP (%BW), GXT—time to exhaustion, relative lower body anaerobic average power (W/kg), and maximal lactic acid concentration showed their relevance accordingly.

Effects of a Congested Fixture Period on Speed and Power Performance of Elite Young Soccer Players.

To investigate the effects of a match-congested period on straight and curve sprint performance, change of direction (COD) speed and deficit, vertical jumping ability, and half-squat (HS) mean propulsive power (MPP) output in young soccer players. A total of 15 under-20 elite male soccer players participated in 14 matches over 8 weeks. The following assessments were performed before and after the congested fixture period: squat and countermovement jumps, 17-m linear sprint, curve sprint test for the "good" (CSGS) and "weak" (CSWS) sides, modified 17-m Zigzag test, and HS MPP. Magnitude-based inferences and a paired t test were used to analyze pre-post changes in the assessed variables. Very likely (P < .05) decreases were noticed in 17-m sprint velocity (effect size [ES] [90% confidence limit; CL], -0.56 [-0.32 to -0.81]) and CSGS (ES [90% CL], -0.72 [-0.40 to 1.03]) after the 8-week period. A possible but nonsignificant impairment was revealed in CSWS (ES [90% CL], -0.18 [0.03 to -0.39]), and countermovement jump (ES [90% CL], -0.21 [-0.54 to 0.12]). Zigzag velocity (ES [90% CL], -2.90 [-2.45 to -3.36]) and COD deficit (ES [90% CL], 0.86 [0.52 to 1.20]) were almost certainly and significantly (P < .05) reduced and increased, respectively, after the match-congested period. An almost certain and significant (P < .05) reduction was found in HS MPP (ES [90% CL], -1.18 [-0.76 to -1.61]). Straight and curve sprint velocity, COD speed and deficit, and HS MPP were impaired after the match-congested period. Vertical jump height was possibly decreased. Seasonal phases comprising high volumes of soccer-specific training and competition seem to be detrimental to speed-power qualities in under-20 elite soccer players.

Hydrogen Rich Water Consumption Positively Affects Muscle Performance, Lactate Response, and Alleviates Delayed Onset of Muscle Soreness After Resistance Training.

Botek, M, Krejčí, J, McKune, A, Valenta, M, and Sládečková, B. Hydrogen rich water consumption positively affects muscle performance, lactate response, and alleviates delayed onset of muscle soreness after resistance training. J Strength Cond Res 36(10): 2792-2799, 2022-Positive outcomes of hydrogen rich water (HRW) supplementation on endurance performance have been shown, but the effects of HRW in resistance training are unclear. The aim of this study was to assess the effects of 1,260 ml of HRW intake on physiological, perceptual, and performance responses to a resistance training and after 24 hours of recovery. This randomized, double-blinded placebo-controlled cross-over study included 12 men aged 23.8 ± 1.9 years. Subjects performed a half squat, knee flexion, and extension exercises with the load set at 70% of 1 repetition maximum for 3 sets (10 reps/set). Lunges were performed with a load of 30% of body mass for 3 sets (20 reps/set). Time of each set, lactate, and ratings of perceived exertion were assessed mid-way through exercise and immediately after the exercise. Creatine kinase, muscle soreness visual analog scale ratings, countermovement jump, and heart rate variability were evaluated before the training and at 30 minutes, 6, and 24 hours of recovery. Lunges were performed faster with HRW compared with placebo ( p < 0.001). Hydrogen rich water reduced lactate at mid-way and immediately after the exercise (HRW: 5.3 ± 2.1 and 5.1 ± 2.2, placebo: 6.5 ± 1.8 and 6.3 ± 2.2 mmol·L -1 , p ≤ 0.008). Visual analog scale ratings were significantly lower with HRW (26 ± 11 vs. 41 ± 20 mm, p = 0.002) after 24 hours of recovery. In conclusion, an acute intermittent HRW hydration improved muscle function, reduced the lactate response, and alleviated delayed onset of muscle soreness.

Morning Priming Exercise Strategy to Enhance Afternoon Performance in Young Elite Soccer Players.

To compare the effects of different modalities of morning priming exercise on afternoon physical performance with the associated hormonal and psychophysiological responses in young soccer players. In a randomized counterbalanced crossover design, 12 young soccer players completed 3 different morning conditions on 3 different days: repeated-sprint running (6 × 40m), easy exercise (4 × 12 fast half squats, 6 speed ladder drills, and 20-m sprints), and control (no exercise). Blood testosterone and cortisol concentrations were assessed upon arrival (approximately 8:30AM) and approximately 5hours and 30minutes later. Body temperature, self-reported mood, quadriceps neuromuscular function (maximal voluntary contraction, voluntary activation, rate of torque development, and twitch contractile properties), jump, and sprint performance were evaluated twice per day, while rating of perceived exertion, motivation, and the Yo-Yo Intermittent Recovery level 2 (IR2) tests were assessed once per day. Compared with the control, repeated-sprint running induced a possible positive effect on testosterone (+11.6%) but a possible to very likely negative effect on twitch contractile properties (-13.0%), jump height (-1.4%), and Yo-Yo IR2 (-7.1%). On the other hand, easy exercise had an unclear effect on testosterone (-3.3%), resulted in lower self-reported fatigue (-31.0%) and cortisol (-12.9%), and had a possible positive effect on the rate of torque development (+4.3%) and Yo-Yo IR2 (+6.5%) compared with the control. Players' testosterone levels were positively influenced by repeated-sprint running, but this did not translate into better physical function, as both muscular and endurance performance were reduced. Easy exercise seemed to be suitable to optimize the physical performance and psychophysiological state of young soccer players.

10 km performance prediction by metabolic and mechanical variables: influence of performance level and post-submaximal running jump potentiation

ABSTRACT We aimed to develop models to explain performance and pacing during a 10-km running trial. Well-trained runners (n = 27, VO2max = 62.3 ± 4.5 mL·kg−1·min−1) divided into High (HPG, T10km = 33.9 ± 1.2 min, n = 9) and Low (LPG, T10km = 37.9 ± 1.2 min, n = 18) performers completed, in different days, the half squat and loaded squat jump (LSJ) exercises (1st day), an incremental test and a submaximal running bout to induce jump potentiation (2nd day), and a 10-km time trial (3rd day). Pacing was significantly different between performance groups (p < 0.05). The inclusion of mechanical and metabolic variables increased the explained variance in performance (LPG, r2adj = 0.87, p < 0.001; HPG, r2adj = 0.99 p < 0.01). Analysis between potentiation and non-potentiation groups revealed significant differences for the speed in the last 400 m (p = 0.02), and in the final RPE (p = 0.03). Performance and pacing can be explained by combining metabolic and mechanical variables and should be controlled by performance level. The relationship between jump potentiation and speed during the last 400 m may suggest that post-activation performance enhancement could be involved in pacing regulation.

The acute effects of different high-intensity conditioning activities on sprint performance differ between sprinters of different strength and power characteristics

The purpose of the present study was to examine the effect of different conditioning activities (CAs) on short-term increase in sprint performance. In twelve male sprinters (21.1±2.6 years, 100 m performance: 11.5±0.6 s) their body composition, half squat maximum strength, 100 m sprinting and countermovement jump performances were evaluated. The performance of a 50 m sprint (splits at 10 m, 30 m and 50 m) was evaluated before and 5, 10 and 15 min after four postactivation performance enhancement CAs on different occasions: [1] 3 sets x 4 s maximum isometric half squat (IHF), [2] 3 sets x 3 consecutive countermovement jumps (cCMJs), [3] 3 repetitions x 30 m overspeed sprinting (OVSP) and [4] dynamic submaximal half squat (2 sets x 2 reps x 90% of 1-RM half squat; HSQ). Significant improvements of sprinting performance were found 10 and 15 min following the cCMJs, OVSP and HSQ’s interventions, in all distances (p&amp;lt;.05; -2.14±1.21% and -3.56±2.47%), without any significant difference between these interventions and time points (p&amp;gt;.05). Significant inter-individual differences were found in the magnitude of sprint performance improvements as well as in the optimal time window (p&amp;lt;.05), with the stronger sprinters responding better after HSQs, while the more powerful sprinters after cCMJs and OVSPs. In conclusion, it seems that cCMJs, OVSP and HSQ can acutely increase sprinting performance after 10 min, but CA’s induced increases in sprinting performance are highly related to the strength and power characteristics of each sprinter.

Effect of power on agility, linear speed and change of direction deficit in female soccer players

Introduction: The aim of the study was to examine relationships between power of the lower limb and agility, speed, and change of direction (COD) deficit in professional female soccer players. Material and methods: Thirty-three elite Polish Extraliga league soccer players (aged 22 ±5 years; body height 166 ± 4 cm; body weight 58 ± 8 kg) performed the following fitness tests: lower limb muscle power (Leg Press, Half Squat, Counter Movement Jump), straight linear speed (SLS 20 m), and COD speed ( Zig-Zag test, COD deficit). Using the median value as a reference, the players were subdivided into two groups (n=17; n=16) according to their LP, HS 60% 1RM, CMJ (High values below median = stronger group and Low = weaker group ). Results: The COD deficit was calculated as the difference between the 20m speed and the Zig-Zag test. The stronger group was better than the weaker group in SLS 20m (p&lt;0.05; ES=1.23; 0.83; 0.93), but in the Zig-Zag agility test, the difference in the results was not statistically significant (p&gt;0.05; ES=0.48; 0.34; 0.34) and this affected the COD deficit, which was higher (p&lt;0.05; ES=0.9; 0.73; 0.72). The most important finding was that the stronger group had a higher COD deficit and its improvement (reduction) occurs only if the results of the agility test are improved (through agility training) [Ydeficit All groups=0.10+0.87*20m - 0.83* Zig-Zag]. Increasing power (HS, LP) lead to the improvement in SLS p&lt;0.05, not to COD abilities. Conclusion: This can be useful for coaches during agility training and to improve COD deficit in soccer players and women in general.

Effects of a 5-Week Linear Periodization Program on Maximal Strength and Speed on Elite Squash Players

Context: Participation in squash requires high efficiency in agility, speed, reaction time and repetitive muscular endurance, aerobic and anaerobic capacities. Standard traditional periodization to reach optimal physical fitness for squash is limited. Therefore, this study aims to find a more alternative approach in training design. Objective: The purpose of this article aims to highlight the benefits of a 5-week linear strength and conditioning program to help improve strength and speed in elite squash players. Design: Case study. Setting: Field research. Participants: 3 male and 2 female Singapore elite squash players in preparation for the 2019 South East Asian Games. Intervention(s): 5-week linear periodization program was a sport specific injury prevention training with a total of 12 special strength sessions, 4 hypertrophy sessions, and 3 speed and plyometric sessions. Main Outcome Measure(s): 1) Maximal strength tests, the athletes were guided into performing a 1-repetition max (RM) half squat test, 1RM single leg adductor test, 2) muscular endurance tests,1-minute push up test, 1-minute sit up test, and 3) maximal speed tests, a 20-meter Sprint test. Tests were conducted before training program and after 5-week linear periodization program. Results: Significant improvement for 1-RM half squat test, 1RM single leg adductor test, 1-minute push up test, 1-minute sit up test and 20-meter sprint test were noted after 5 weeks of linear periodization program. There were significantly higher rates of improvement in strength compared to speed. Conclusions: 5-week linear periodization training program displayed significant improvement in strength, muscular endurance and speed suggesting that a linear strength and conditioning program can be highly beneficial for squash players.

Acute Neuromuscular Responses to Whole-Body Vibration of Systemic Lupus Erythematosus Individuals: A Randomized Pilot Study

Background: Glucocorticoid induced osteoporosis (GIOP) is one of the most important causes of morbidity in lupus individuals. Whole body vibration exercises (WBVE) may be a safe alternative to prevent and amend muscular and bone damage, and decrease muscle related risk factors for falls. It is possible to evaluate neuromuscular responses to the WBVE through surface electromyography (sEMG). Objective: To analyze and compare the acute responses of the WBVE on sEMG of lower limbs of female systemic lupus erythematosus (SLE) individuals with chronic glucocorticoid use with and without bone impairments and non-lupus controls. Methods: All patients (non-lupus and with SLE) had a dual-energy X-ray absorptiometry (DXA) scan (body composition, bone composition right hip, lumbar segment and whole body). After DXA, they were divided into three groups: SLE with osteopenia (OPIA) (SLE OPIA), SLE without OP or OPIA (SLE) and non-lupus individuals as control (CG). Twenty-seven women were submitted to WBVE, on different frequencies with the same amplitude. The experiment was performed over two days, 48 h apart. The individuals stood at a half squat position on a vertical vibrating platform at different frequencies with the same amplitude on both days. Vastus lateralis (VL), gastrocnemius medialis (GM) and tibialis anterioris (TA) sEMG analyses were undertaken simultaneously while performing the exercises, in a randomized manner. Results: There were no differences between sarcopenia index among groups, despite the bone impairment of the SLE OPIA group. The greatest muscle activation occurred in the lower frequency applied for VL. A group x frequency difference was found only for GM (p = 0.034; η2 = 0.272). Conclusion: The results indicate that lupus individuals have similar neuromuscular activity to the WBVE as non-lupus controls. Moreover, this suggests that WBVE is a safe and viable physical exercise for lupus individuals with chronic glucocorticoid induced osteoporosis.

Delayed potentiation effects on neuromuscular performance after optimal load and high load resistance priming sessions using velocity loss

Aim: (i) to compare the effects of two different low-volume resistance priming sessions, where the external load is modified on neuromuscular performance after 6 h of rest; and (ii) to identify the effects on psychological readiness in participants with resistance training experience. Methods: Eleven participants (Body mass: 77.0 ± 8.9 kg; Body height: 1.76 ± 0.08 m; Half squat repetition maximum: 139.8 ± 22.4 kg) performed the priming session under three experimental conditions in a randomized and cross-over design during the morning. The control (CON) condition: no resistance training, “optimal load” (OL) condition: two half-squat sets with a velocity loss of around 20% were performed with the “optimal load”, and 80% of repetition maximum (80% RM) condition: 2 half-squat sets with a velocity loss of around 20% were performed with the 80% RM. Countermovement jump (CMJ), mean power with OL (MPOL) and 80% RM (MP80RM), and mean velocity with OL (MVOL) and 80% RM (MV80RM) were assessed six hours after the intervention. Subjective readiness was also recorded prior to resistance training and evaluation. Significance was set at p < 0.05. Results: CMJ was higher after the 80% RM intervention than CON (p < 0.001; Δ = 6.5% [3.4–9.5]). MPOL and MVOL seemed to be unaffected by both morning sessions. Higher MP80RM (p = 0.044; Δ = 9.7% [4.0–15.6]; d = 0.24[0.10–0.37]) and MV80RM (p = 0.004; Δ = 8.1% [3.2–13.3]; d = 0.32[0.13–0.52]) after 80% RM than after CON were observed. No effect was observed on psychological readiness. Conclusions: 80% RM priming session increased CMJ height and the capacity to generate power and velocity under a high-load condition without any effect on psychological readiness.

Traditional Free-Weight Vs. Variable Resistance Training Applied to Elite Young Soccer Players During a Short Preseason: Effects on Strength, Speed, and Power Performance.

Loturco, I, Pereira, LA, Reis, VP, Zanetti, V, Bishop, C, and Mcguigan, MR. Traditional free-weight vs. variable resistance training applied to elite young soccer players during a short preseason: Effects on strength, speed, and power performance. J Strength Cond Res 36(12): 3432-3439, 2022-Maximizing the neuromuscular capacities of players is a critical challenge during short soccer preseasons. This study compared the effects of 2 strength-power training regimes, on the strength, speed, and power performance of elite young soccer players during a 4-week preseason. Twenty-five under-20 players from the same club were pair matched in 2 training groups as follows: traditional training group (TTG) ( n = 13), athletes performed half-squat (HS) and jump-squat (JS) exercises as traditionally prescribed, and elastic band (EB) group (EBG) ( n = 12), athletes performed HS and JS with EB attached to the barbell. Vertical jump height, 20-m sprint velocity, change of direction (COD) speed, HS and JS power, and 1 repetition maximum (1RM) in the HS were assessed before, after 2-week, and after 4-week of training. A two-way analysis of variance with repeated measures was used to assess the effects of both training protocols over the experimental period. Both strategies were effective for significantly improving HS and JS power (effect sizes [ESs] = 1.00-1.77), HS 1RM (ES = 1.68 and 1.51 for TTG and EBG, respectively), vertical jumping ability (ES = 0.37-0.65), and COD speed (ES = 0.81 and 0.39 for TTG and EBG, respectively), when comparing premeasures and postmeasures. By contrast, both TTG and EBG failed to increase 20-m sprint velocity (ES ranging between -0.54 and 0.23). In conclusion, both training schemes were able to improve the strength and power performance but not the sprint capacity of young soccer players. To accelerate strength gains over very-short time periods (i.e., 2 weeks), variable resistance training may be advantageous. Conversely, to optimize power adaptations in ballistic exercises across a similar time period, traditional free-weight training may be preferred.

Effects of low intensity resistance training of blood flow restriction with different occlusion pressure on lower limb muscle and cardiopulmonary function of college students

Objective: The study compared the effects of low intensity resistance training with blood flow restriction (BFR) with different occlusion pressure on lower limb muscle and cardiopulmonary function. Methods: Twenty-seven college students were randomly divided into three groups by different occlusion pressure: 0 mmHg (group C), 120 mmHg (group L) and 180 mmHg (group H). Before and after training (3 times a week for 12 weeks) with an inflatable cuff (20% 1RM, half squat), the muscle thickness(MTH)of rectus femoris and medius femoris, relative peak knee extensor moment(rM), peak power(P), relative maximal oxygen uptake(rVO2max), stroke volume(SV), cardiac output(CO), ejection fraction(EF) and other indicators were measured for all subjects. Results: When compared with pre-training, and rectus femoris, the MTH of medius femoris, rM, rVO2max, SV, CO and EF were significantly increased in group L and group H after 12 weeks training(P＜0.05, P＜0.01), as well as compared with group C after training(P＜0.05, P＜0.01). There was no significant difference between group L and group H after training. Conclusion: BFR training protocols under 120 mmHg or 180 mmHg pressure were effective in improving muscle and cardiopulmonary function.

Effect of Three Half-Squat Protocols on the Tensiomyographic Twitch Response and Tissue Damage of the Rectus Femoris and the Biceps Femoris.

The aim of this study was to analyse the acute effects of a concentric exercise and two different eccentric overload exercises (EOEs) on blood markers of muscle damage (i.e. creatine kinase [CK], lactate dehydrogenase [LDH], myoglobin [Myo], and malondialdehyde [MDA]) and muscle contractile properties. Ten healthy, young (27 ± 1.5 years, 179 ± 6 cm, 78.7 ± 10.8 kg), physically active men (3.5 ± 1.9 h·w-1) randomly performed three training sessions using the following protocols: a half-squat (HS) as a concentric exercise, and exercises using Versapulley (VP) or YoYo isoinertial technology (YIT) as EOEs (4 x 7 repetitions with a 2 min rest interval between sets). Blood samples and tensiomyography measurements were obtained after each training session. Repeated measures analysis of variance (ANOVA) followed by the Tukey test was used to detect differences between the four time points of each variable. The standardized difference or effect size (ES, 90% confidence limit) in the selected variables was calculated using the basal SD. After all exercises, a greater activity of CK, LDH, and concentration of Myo, and MDA were found compared to baseline values (p < 0.05). A substantially greater activity of CK, LDH, and Myo concentration, but not MDA, were found after EOEs when compared to the HS protocol. Substantially lower tensiomyography results in the rectus femoris (RF) were reported, irrespective of the exercise mode performed. Also, no substantial differences were obtained in the biceps femoris (BF) between EOEs and the HS protocol. Time of contraction (Tc) in the RF was possibly to very likely lower in the HS in comparison to EOEs. Additionally, muscular displacement (Dm) in the RF was substantially lower in the HS compared to EOEs. VP produced higher concentrations of damage markers than YIT and concentric exercise did. Furthermore, tensiomyography variables showed similar activation in both exercises, although higher specific fatigue (in the RF) was registered in the traditional HS.

Relationships Between Measures of Functional and Isometric Lower Body Strength, Aerobic Capacity, Anaerobic Power, Sprint and Countermovement Jump Performance in Professional Soccer Players.

The purpose of this study was to assess a wide range of physiological and performance variables and investigate whether and to what extent these variables are associated with each other in soccer. Twenty-five male soccer players (25.1 ± 4.56 years; body mass, 75.2 ± 5.92 kg; body height, 180.6 ± 5.45 cm) performed: 5- and 30-m sprints (T5m and T30m, respectively), 1-repetition-maximum (1RM) half squat, maximal voluntary isometric contraction (MVIC) of the knee extensors, countermovement jump (CMJ) to obtain vertical jump height (CMJheight) and power output (CMJpower), the 10-s Wingate Anaerobic Test (WAnT) to obtain peak power (Pmax), and the 20-m multi-stage shuttle run test (MST) to evaluate aerobic capacity. 1RM, MVIC, and Pmax were normalized to body mass. Large negative correlations were found between sprint times and 1RM half back squat/BM (r = -0.510 to -0.570, r2 = 0.260–0.325, both p < 0.01) and Pmax/BM (r = -0.501, r2 = 0.251, p < 0.01). T30m most strongly and negatively correlated with CMJheight (r = -0.744, r2 = 0.554, p < 0.001). WAnT-determined Pmax showed a very large correlation between absolute Pmax and knee-extensor MVIC (r = 0.827, r2 = 0.684, p < 0.001) and large correlations between absolute Pmax and 1RM half squat (r = 0.674, r2 = 0.454, p < 0.001) and CMJpower (r = 0.579, r2 = 0.335, p < 0.01). We also identified a large inverse relationship between CMJheight and T30m (r = -0.744, r2 = 0.554, p < 0.001) and large positive correlation between CMJheight and MVIC/BM (r = 0.702, p < 0.001). The results demonstrate that elite soccer players with greater lower body strength (quantified by the MVIC of the knee extensor and the 1RM half squat) show better sprint and CMJ performance, suggesting the incorporation of soccer-specific resistance training to develop lower body musculature and therefore maximize sprinting ability. The higher correlation coefficients found between T30m and the physiological and athletic measures compared with T5m promote the use of this sprint distance when assessing performance. The use of relative measures (normalized to body mass) is advisable when comparing strength variables with sprint and CMJ performance or anaerobic power. Considering the correlations of WAnT-determined Pmax versus CMJpower, coaches should administer tests that assess jumping and linear sprint performance rather than the cycling-specific WAnT.

No Change - No Gain; The Effect of Age, Sex, Selected Genes and Training on Physiological and Performance Adaptations in Cross-Country Skiing.

The aim was to investigate the effect of training, sex, age and selected genes on physiological and performance variables and adaptations before, and during 6 months of training in well-trained cross-country skiers. National-level cross-country skiers were recruited for a 6 months observational study (pre – post 1 – post 2 test). All participants were tested in an outside double poling time trial (TTDP), maximal oxygen uptake in running (RUN-VO2max), peak oxygen uptake in double poling (DP-VO2peak), lactate threshold (LT) and oxygen cost of double poling (CDP), jump height and maximal strength (1RM) in half squat and pull-down. Blood samples were drawn to genetically screen the participants for the ACTN3 R577X, ACE I/D, PPARGC1A rs8192678, PPARG rs1801282, PPARA rs4253778, ACSL1 rs6552828, and IL6 rs1474347 polymorphisms. The skiers were instructed to train according to their own training programs and report all training in training diaries based on heart rate measures from May to October. 29 skiers completed all testing and registered their training sufficiently throughout the study period. At pre-test, significant sex and age differences were observed in TTDP (p < 0.01), DP-VO2peak (p < 0.01), CDP (p < 0.05), MAS (p < 0.01), LTv (p < 0.01), 1RM half squat (p < 0.01), and 1RM pull-down (p < 0.01). For sex, there was also a significant difference in RUN-VO2max (p < 0.01). No major differences were detected in physiological or performance variables based on genotypes. Total training volume ranged from 357.5 to 1056.8 min per week between participants, with a training intensity distribution of 90–5–5% in low-, moderate- and high-intensity training, respectively. Total training volume and ski-specific training increased significantly (p < 0.05) throughout the study period for the whole group, while the training intensity distribution was maintained. No physiological or performance variables improved during the 6 months of training for the whole group. No differences were observed in training progression or training adaptation between sexes or age-groups. In conclusion, sex and age affected physiological and performance variables, with only a minor impact from selected genes, at baseline. However, minor to no effect of sex, age, selected genes or the participants training were shown on training adaptations. Increased total training volume did not affect physiological and performance variables.

Management of Medial Collateral Ligament Insufficiency During Total Knee Arthroplasty with a Screw and Rectangular Spiked Washer: A Case Series of 14 Patients

ObjectiveTo describe the technique of primary repair of medial collateral ligament (MCL) insufficiency using a screw and rectangular spiked washer in a case series of 14 patients.MethodsFourteen patients undergoing MCL repair by a screw and rectangular spiked washer during TKA between March 2018 and March 2019 were retrospectively reviewed. Among them, half injuries were avulsion of the femoral origin, and the other half were MCL laxity. There were 12 women and two men included in the study, with an average age of 63.6 years (range, 49–79 years) at the time of surgery. This series were followed up with a focus on range of motion (ROM), coronal alignment, Hospital for Special Surgery (HSS) knee scores, their subjective sense of joint instability, and related complications. At the last follow‐up, function of the MCL was assessed by manually applying a valgus stress to the knee at both 0° and 30° of knee flexion.ResultsThe mean follow‐up time for all patients was 15.6 months (range, 13–20 months). Repair of the MCL was successful in all patients. ROM improved from a mean of 70.7° ± 35.1° before surgery to 103.9° ± 6.8° at latest follow‐up (P = 0.001). All patients were able to perform a half squat easily, but none were able to do full squatting. The mean preoperative HSS score was 43.6 ± 13.4 and increased to a mean of 85.6 ± 3.8 postoperatively (P < 0.001). The femorotibial angle improved from a mean of −3.22° ± 9.47° before surgery to a mean of 5.16° ± 3.14° at the final follow‐up (P = 0.006). At the time of final follow‐up, no patient required revision and manipulation under anesthesia following the index arthroplasty. No radiolucencies or migration were observed in association with the knee prostheses. No displacement of the screw and rectangular spiked washer was found. There were no clinical complications. No patient reported subjective instability of the knee. Upon physical examination, no patient was found to have laxity in the coronal plane in either 30° of flexion or full extension.ConclusionsThe screw and rectangular spiked washer is a simple and effective method for treating MCL sufficiency in TKA, and a study with a larger cohort and extended follow‐up is requisite to claim its role in preventing coronal instability and component failure.

Effects of resistance training intensity on sleep quality and strength recovery in trained men: a randomized cross-over study.

Resistance training (RT) variables can affect sleep quality, strength recovery and performance. The aim of this study was to examine the acute effect of RT leading to failure vs. non-failure on sleep quality (SQ), heart rate variability (HRV) overnight and one-repetition maximum (1-RM) performance 24 hours after training. Fifteen resistance-trained male athletes (age: 23.4 ± 2.4 years; height 178.0 ± 7.6 cm; weight: 78.2 ± 10.6 kg) performed two training sessions in a randomized order, leading to failure (4x10) or non-failure (5x8(10) repetitions), with 90 seconds for resting between sets at 75% 1-RM in bench press (BP) and half squat (HS). The day after, the participants completed the predicted 1-RM test for both exercises. In addition, the subjective and actigraphic SQ and HRV during sleep were measured after each training session. The day after the training protocol leading to failure, the 1-RM of BP (MD = 7.24 kg; -7.2%; p < 0.001) and HS (MD = 20.20 kg; -11.1%; p < 0.001) decreased. However, this parameter did not decrease after a non-failure RT session. No differences were observed between failure and non-failure training sessions on SQ and HRV; therefore, both types of training sessions similarly affected the SQ and the autonomic modulation during the night after the training session. This study provides an insight into the influence of different training strategies on SQ, strength performance and recovery after moderate- to high-demand training. This information could be useful especially for professional coaches, weightlifters and bodybuilders, due to the potential influence on the programming processes.

Resistance Exercise With Blood Flow Restriction Under Different Occlusion Pressure On Muscular Performance

PURPOSE: The study compared the effect of low intensity resistance exercise with blood flow restriction (BFR) in the proximal thigh under different occlusion pressure on muscle morphology and function. METHODS: Twenty-seven healthy college students who had no training experience were randomly divided into three groups by different occlusion pressure: 0 mmHg (CON), 120 mmHg (LBFR) and 180 mmHg (HBFR). Before and after 12 weeks training with an inflatable cuff (20% 1RM, half squat, 4 sets, 75 repetitions in total, 3 days a week) in three groups, the muscle thickness (MT) of rectus femoris and medius femoris were assessed by ultrasound for all subjects. The maximal isokinetic torque (ITmax), relative maximal isokinetic torque(R-ITmax) and maximal power (Pmax) were measured at angular velocities of 60°/sec by ISOMED 2000 System in dominant low limb of all subjects. RESULTS: The MT of rectus femoris and medius femoris in LBFR increased after training compared with pre-training (2.12±0.22 vs. 1.99±0.16 cm and 2.01±0.09 vs. 1.82±0.15 cm, p<0.05), as well as in HBFR (2.15±0.16 vs. 1.95±0.19 cm and 2.02±0.19 vs. 1.86±0.14 cm, p<0.01). The ITmax after training were higher than pre-training not only in LBFR (213.00±26.04 vs. 204.56±29.16 Nm, p<0.01), but also in HBFR (217.00±20.13 vs. 190.33±15.71Nm, p<0.01). A significant increase in R-ITmax was noted in LBFR than pre-training (2.87±0.35 vs. 2.74±0.38 Nm/kg, p<0.01), and also in HBFR (2.94±0.26 vs. 2.57±0.20 Nm/kg, p<0.01 ). However, there was no significant increase in Pmax after training in LBFR (124.78±18.93 vs. 119.89±13.32W, p>0.05) or HBFR (122.56±16.44 vs. 120.26±17.43W, p>0.05). There was no significant change in MT, ITmax, R-ITmax and Pmax before and after training in CON (p>0.05). Besides, the MT, ITmax and R-ITmax in LBFR and HBFR had a significant change compared with CON respectively after training (p<0.05). There was no any significant difference in the MT, ITmax, R-ITmax, Pmax between LBFR and HBFR after training (p>0.05). CONCLUSION: BFR training protocols under 120mmHg or 180mmHg pressure are effective in improving muscular morphology and function. But the higher occlusion pressure may not have more benefit in improving muscular performance than the lower occlusion pressure.