The Effect of a Single Session of Plyometric Training Per Week on Fitness Parameters in Professional Female Soccer Players: A Randomized Controlled Trial.

ABSTRACT: Nonnato, A, Hulton, AT, Brownlee, TE, and Beato, M. The effect of a single session of plyometric training per week on fitness parameters in professional female soccer players. A randomized controlled trial. J Strength Cond Res 36(4): 1046-1052, 2022-As the interest and popularity of female soccer has increased over the last few decades, there still lacks research conducted with the elite population, specifically ecological training interventions during the competitive season. Therefore, the aim of this study was to compare the effectiveness of 12 weeks (undertaken once a week) of plyometric (PLY) training on physical performance in professional female soccer players during the season. Using a randomized controlled trial design, 16 players were included in the current study (mean ± SD; age 23 ± 4 years, weight 60.3 ± 4.9 kg, height 167 ± 3.7 cm) and randomized in PLY (n = 8) and Control groups (CON, n = 8), respectively. Squat jump (SJ), counter movement jump (CMJ), long jump (LJ), single-leg triple jump distance test (triple jump test), changes of direction 505 test (505-COD), and sprint 10 and 30 m were performed before and after 12 weeks of PLY training. Significant within-group differences were found in triple jump test dominant (p = 0.031, effect size [ES] = moderate) and nondominant limb (p = 0.021, ES = moderate) and sprint 10 m (p = 0.05, ES = large), whereas the CON did not report any positive variation. However, neither group reported significant variation in SJ, CMJ, LJ, 505-COD, and sprint 30 m (underlining the difficulties in obtain meaningful variation in season). These findings have strong practical applications because this study showed for the first time that a single session a week of plyometric training can significantly increase sport-specific fitness parameters in professional female soccer players during the season.

Exogenous carbohydrate and regulation of muscle carbohydrate utilisation during exercise.

PURPOSE: Carbohydrates (CHO) are one of the fundamental energy sources during prolonged steady state and intermittent exercise. The consumption of exogenous CHO during exercise is common place, with the aim to enhance sporting performance. Despite the popularity around exogenous CHO use, the process by which CHO is regulated from intake to its use in the working muscle is still not fully appreciated. Recent studies utilizing the hyperglycaemic glucose clamp technique have shed light on some of the potential barriers to CHO utilisation during exercise. The present review addresses the role of exogenous CHO utilisation during exercise, with a focus on potential mechanisms involved, from glucose uptake to glucose delivery and oxidation at the different stages of regulation. METHODS: Narrative review. RESULTS: A number of potential barriers were identified, including gastric emptying, intestinal absorption, blood flow (splanchnic and muscle), muscle uptake and oxidation. The relocation of glucose transporters plays a key role in the regulation of CHO, particularly in epithelial cells and subsequent transport into the blood. Limitations are also apparent when CHO is infused, particularly with regards to blood flow and uptake within the muscle. CONCLUSION: We highlight a number of potential barriers involved with the regulation of both ingested and infused CHO during exercise. Future work on the influence of longitudinal training within the regulation processes (such as the gut) is warranted to further understand the optimal type, dose and method of CHO delivery to enhance sporting performance.

A 3-day dietary manipulation affects muscle glycogen and results in modifications of carbohydrate and fat metabolism during exercise when hyperglycaemic.

PURPOSE: The effect of hyperglycaemia on exercise with low and elevated muscle glycogen on glucose utilization (GUR), carbohydrate and fat oxidation, hormonal and metabolite responses, as well as rating of perceived exertion (RPE) were explored. METHODS: Five healthy trained males were exercised for 90 min at 70% V̇O2max in two trials, while glucose was infused intravenously at rates to "clamp" blood glucose at 12 mM. On one occasion, participants were 'loaded' with carbohydrate (CHO-L), whilst on a separate occasion, participants were glycogen depleted (CHO-D). Prior exercise and dietary manipulations produced the 'loaded' and 'depleted' states. RESULTS: The CHO-L and CHO-D conditions resulted in muscle glycogen concentrations of 377 and 159 mmol/g dw, respectively. Hyperglycaemia elevated plasma insulin concentrations with higher levels for CHO-L than for CHO-D (P < 0.01). Conversely, CHO-D elevated plasma adrenaline and noradrenaline higher than CHO-L (P < 0.05). Plasma fat metabolites (NEFA, ß-hydroxybutyrate, and glycerol) were higher under CHO-D than CHO-L (P < 0.01). The resultant was that the rates of total carbohydrate and fat oxidation were elevated and depressed for loaded CHO-L vs CHO-D respectively (P < 0.01), although no difference was found for GUR (P > 0.05). The RPE over the exercise period was higher for CHO-D than CHO-L (P < 0.05). CONCLUSION: Hyperglycaemia during exercise, when muscle glycogen is reduced, attenuates insulin but promotes catecholamines and fat metabolites. The effect is a subsequent elevation of fat oxidation, a reduction in CHO oxidation without a concomitant increase in GUR, and an increase in RPE.

Hyperinsulinaemia and hyperglycaemia promote glucose utilization and storage during low- and high-intensity exercise.

PURPOSE: The effect of hyperglycaemia with and without additional insulin was explored at a low and high intensity of exercise (40% vs 70% VO2peak) on glucose utilization (GUR), carbohydrate oxidation, non-oxidative glucose disposal (NOGD), and muscle glycogen. METHODS: Eight healthy trained males were exercised for 120 min in four trials, twice at 40% VO2peak and twice at 70% VO2peak, while glucose was infused intravenously (40%G; 70%G) at rates to "clamp" blood glucose at 10 mM. On one occasion at each exercise intensity, insulin was also infused at 40 mU/m2/per min (i.e. 40%GI and 70%GI). The glucose and insulin infusion began 30 min prior to exercise and throughout exercise. A muscle biopsy was taken at the end of exercise for glycogen analysis. RESULTS: Hyperglycaemia significantly elevated plasma insulin concentration (p < 0.001), although no difference was observed between the exercise intensities. Insulin infusion during both mild and severe exercise resulted in increased insulin concentrations (p < 0.01) and GUR (p < 0.01) compared with glucose (40%GI by 25.2%; 70%GI by 26.2%), but failed to significantly affect carbohydrate, fat and protein oxidation. NOGD was significantly higher for GI trials at both intensities (p < 0.05) with storage occurring during both lower intensities (62.7 ± 19.6 g 40%GI; 127 ± 20.7 g 40%GI) and 70%GI (29.0 ± 20.0 g). Muscle glycogen concentrations were significantly depleted from rest (p < 0.01) after all four trials. CONCLUSION: Hyperinsulinaemia in the presence of hyperglycaemia during both low- and high-intensity exercise promotes GUR and NOGD, but does not significantly affect substrate oxidation.

Addition of Caffeine to a Carbohydrate Feeding Strategy Prior to Intermittent Exercise.

The ergogenic effect of caffeine is well established, although no investigations providing a high carbohydrate feeding strategy (pre-exercise meal=2 g/kg BM) co-ingested with caffeine exist for soccer. This investigation examines the effect of caffeine in addition to a pre-exercise carbohydrate meal and drink mid-way through a soccer simulation. Eight recreational soccer players completed an 85-minute soccer simulation followed by an exercise capacity test (Yo-yo Intermittent Endurance test level 2) on two occasions. Prior to exercise participants consumed a high carbohydrate meal, with placebo or 5 mg/kg BM-1 caffeine. No significant performance effect was identified (p=0.099) despite a 12.8% (109 m) improvement in exercise capacity following caffeine. Rates of carbohydrate and fat oxidation did not differ between conditions and nor were differences apparent for plasma glucose, fatty acids, glycerol, ß-hydroxybutyrate (p>0.05). However, an increase in lactate was observed for caffeine (p=0.039). A significant condition effect on rating of perceived exertion was identified (p<0.001), with the overall mean for the protocol lowered to 11.7±0.9 au for caffeine compared to 12.8±1.3 au. Caffeine supplementation with a carbohydrate feeding strategy failed to affect metabolic and metabolite responses, although reductions in perception of exercise were observed. While a 12.8% increase in exercise capacity was noted the findings were not significant, possibly due to the small sample size.

Positional Differences in Running and Nonrunning Activities During Elite American Football Training.

Ward, PA, Ramsden, S, Coutts, AJ, Hulton, AT, and Drust, B. Positional differences in running and nonrunning activities during elite American football training. J Strength Cond Res XX(X): 000-000, 2017-The aim of this investigation was to describe differences in training loads between position groups within professional American football. Integrated micro technology data were collected on 63 NFL football players during an American football training camp. Five key metrics (total distance, high-speed distance, player load (PL), PL per minute, and total inertial movement analysis [IMA]) served to quantify both running and nonrunning activities. Players were classified into position groups (defensive back [DB], defensive linemen [DL], linebacker, offensive linemen [OL], quarterback, running back, tight end, and wide receiver [WR]). Training sessions were identified by their relationship to the upcoming match (e.g., -4, -3, and -2). Running and nonrunning activities varied between position groups relative to the training day. Differences in total distance between DB and WR were observed to be unclear across the 3 training days (game day [GD] -4: 74 ± 392 m; GD -3: -122 ± 348 m; and GD -2: -222 ± 371 m). However, moderate to large differences were observed between these 2 positions and the other positional groups. A similar relationship was observed in PL and PL per minute, with the DB and WR groups performing greater amounts of load compared with other positional groups. Differences in high-speed distance varied across positional groups, indicating different outputs based on ergonomic demands. The OL and DL groups ran less but engaged in a higher amount of nonrunning activities (total IMA) with differences ranging from moderate to large across the 3 training days. Total IMA differences between offensive and defensive linemen were unclear on GD -4 (-4 ± 9) and GD -2 (-2 ± 8) and likely moderate on GD -3 (-9 ± 9). Positional differences with regard to running and nonrunning activities highlight the existence of position-specific training within a training microcycle. In addition, total IMA provides a useful metric for quantifying sport-specific movements within the game of American football.

Evaluation of the external and internal workload in female futsal players.

Match analysis technology has been extensively used in football, but there is limited literature on its use in futsal. Despite its increased popularity, the female futsal game model has never been quantified. The aim of this study was to quantify locomotor and mechanical activities performed during a non-competitive female futsal match, measuring the differences between the first and second half. Sixteen female futsal players of the Italian 2nd division were enrolled (age 27±5 years, height 1.65±0.09 m, body weight 56.9±7.7 kg, BMI 20.9±1.9, fat mass 21.5±2.9%). Locomotor and mechanical activities were recorded by means of the 10 Hz GPS StatSports system. Games were performed on a 38x18 m synthetic grass outdoor pitch. Significant differences were found between the first and second half in total distance (1424±114 and 1313±113 m, p<0.05), relative velocity (70±6 and 64±6 m min-1, p<0.05), high speed running (28±16 and 22±19 m, p<0.05) and high metabolic distance (80 ± 29 and 69 ± 28 m, p<0.05). The match analysis of female futsal matches provides useful information about its external load demands. Female futsal players decreased the workload in the second half compared to the first one during this non-competitive match. It was found that fatigue impairs the performance in the second part of the game. Coaches and physical trainers can obtain useful information to design training programmes taking into account the quantification of locomotor and mechanical activities performed in this study.

Dietary Intake of Soccer Players before, during and after an Official Game: Influence of Competition Level and Playing Position.

Physical demands in soccer differ according to league level and playing position and may influence nutritional requirements. This study examined the effect of competition level and playing position on dietary intake in male soccer players (SP). Diet was weighed and recorded by 123 SP for 3 days; before, on the day, and the day after an official match. SP in the Super League (SL, n = 33) division reported higher (p < 0.05) average three-day energy (195 ± 36 kJ/kg), carbohydrate (6.0 ± 1.1 g/kg), and protein (2.2 ± 0.5 g/kg) intakes compared to the intakes reported by SP in the 2nd (n = 30) (energy: 159 ± 31 kJ/kg; carbohydrate: 4.6 ± 1.2 g/kg; protein: 1.9 ± 0.4 g/kg), 3rd (n = 30) (energy: 153 ± 34 kJ/kg; carbohydrate: 4.5 ± 1.2 g/kg; protein: 1.7 ± 0.4 g/kg), and 4th (n = 30) (energy: 152 ± 36 kJ/kg; carbohydrate: 4.2 ± 1.2 g/kg; protein: 1.7 ± 0.5 g/kg) national leagues (mean ± SD). Furthermore, when data were analyzed by playing position (pooled data), wide midfielders reported higher (p < 0.05) energy (183 ± 33 kJ/kg), carbohydrate (5.4 ± 1.2 g/kg), and fat (1.5 ± 0.4 g/kg) intakes compared to central defenders (energy: 147 ± 37 kJ/kg; carbohydrate: 4.1 ± 1.1 g/kg; fat: 1.2 ± 0.4 g/kg). The dietary intake of SP may differ according to the playing position and competition level, possibly due to different metabolic demands in training and competition.

Energy Requirements and Nutritional Strategies for Male Soccer Players: A Review and Suggestions for Practice.

Soccer is a high intensity intermittent sport, featuring critical events completed at high/maximal intensity which is superimposed onto an aerobic base of lower intensity activities and rest. Due to these varying energic demands and the duration of competition the need for optimal nutritional strategies to offset and delay fatigue are paramount. Over the last 50 years, several investigations have been reported on aspects of soccer be they nutrition-focused or those concerning the demands of the sport. Emanating from these scientific papers, observations have been made on the likely factors which result in the fatigue during match-play. Factors such as muscle glycogen depletion and hypoglycaemia are discussed. Studies on the energy demands of soccer have employed a variety of methodologies which are briefly reviewed and vary between the use of heart rate telemetry to the use of global positioning systems (GPS). Moving on from observations of the energy demands of the sport leads to the major focus of this review which highlights key nutritional strategies to support the preparation and recovery of male soccer players to enhance performance, or at least to enable players to perform adequately. This review examines relevant methodologies in assessing training and competitive energy costs as well as the concomitant energy intakes demanded for successful performance outcomes. In order to bring an applied aspect to the overall findings from areas discussed, some practical ideas of feeding strategies are presented.

The Dose-Effects of Caffeine on Lower Body Maximal Strength, Muscular Endurance, and Rating of Perceived Exertion in Strength-Trained Females.

Caffeine supplementation has shown to be an effective ergogenic aid enhancing athletic performance, although limited research within female populations exists. Therefore, the aim of the investigation was to assess the effect of pre-exercise caffeine supplementation on strength performance and muscular endurance in strength-trained females. In a double-blind, randomised, counterbalanced design, fourteen strength-trained females using hormonal contraception consumed either 3 or 6 mg·kg-1 BM of caffeine or placebo (PLA). Following supplementation, participants performed a one-repetition maximum (1RM) leg press and repetitions to failure (RF) at 60% of their 1RM. During the RF test, rating of perceived exertion (RPE) was recorded every five repetitions and total volume (TV) lifted was calculated. Repeated measures ANOVA revealed that RF (p = 0.010) and TV (p = 0.012) attained significance, with pairwise comparisons indicating a significant difference between 3 mg·kg-1 BM and placebo for RF (p = 0.014), with an effect size of 0.56, and for 6 mg·kg-1 BM (p = 0.036) compared to the placebo, with an effect size of 0.65. No further significance was observed for 1RM or for RPE, and no difference was observed between caffeine trials. Although no impact on lower body muscular strength was observed, doses of 3 and 6 mg·kg-1 BM of caffeine improved lower body muscular endurance in resistance-trained females, which may have a practical application for enhancing resistance training stimuli and improving competitive performance.

The Comparative Methylome and Transcriptome After Change of Direction Compared to Straight Line Running Exercise in Human Skeletal Muscle.

The methylome and transcriptome signatures following exercise that are physiologically and metabolically relevant to sporting contexts such as team sports or health prescription scenarios (e.g., high intensity interval training/HIIT) has not been investigated. To explore this, we performed two different sport/exercise relevant high-intensity running protocols in five male sport team members using a repeated measures design of: (1) change of direction (COD) versus; (2) straight line (ST) running exercise with a wash-out period of at least 2 weeks between trials. Skeletal muscle biopsies collected from the vastus lateralis 30 min and 24 h post exercise, were assayed using 850K methylation arrays and a comparative analysis with recent (subject-unmatched) sprint and acute aerobic exercise meta-analysis transcriptomes was performed. Despite COD and ST exercise being matched for classically defined intensity measures (speed × distance and number of accelerations/decelerations), COD exercise elicited greater movement (GPS-Playerload), physiological (HR), metabolic (lactate) as well as central and peripheral (differential RPE) exertion measures compared with ST exercise, suggesting COD exercise evoked a higher exercise intensity. The exercise response alone across both conditions evoked extensive alterations in the methylome 30 min and 24 h post exercise, particularly in MAPK, AMPK and axon guidance pathways. COD evoked a considerably greater hypomethylated signature across the genome compared with ST exercise, particularly at 30 min post exercise, enriched in: Protein binding, MAPK, AMPK, insulin, and axon guidance pathways. Comparative methylome analysis with sprint running transcriptomes identified considerable overlap, with 49% of genes that were altered at the expression level also differentially methylated after COD exercise. After differential methylated region analysis, we observed that VEGFA and its downstream nuclear transcription factor, NR4A1 had enriched hypomethylation within their promoter regions. VEGFA and NR4A1 were also significantly upregulated in the sprint transcriptome and meta-analysis of exercise transcriptomes. We also confirmed increased gene expression of VEGFA, and considerably larger increases in the expression of canonical metabolic genes PPARGC1A (that encodes PGC1-α) and NR4A3 in COD vs. ST exercise. Overall, we demonstrate that increased physiological/metabolic load via COD exercise in human skeletal muscle evokes considerable epigenetic modifications that are associated with changes in expression of genes responsible for adaptation to exercise.

Manipulation of exercise to rest ratio within set duration on physical and technical outcomes during small-sided games in elite youth soccer players.

Training practices for elite soccer players should take into account specific technical, tactical and physical components. As a consequence of these demands small-sided games (SSGs) have become a popular conditioning tool that replicate the demands encountered during match play. The aim of this investigation was to examine how the manipulation of exercise to rest ratio, within the same overall duration, affected both physical and technical outcomes during SSGs in elite youth soccer. Twelve elite youth soccer players participated in three variations of eight minute 6v6 SSGs. The three variations included eight minutes continuous, 2×4min and 4×2min. Players perceived the continuous 8min block as the hardest (4.5±1.5AU), followed by the 2×4min (3.9±1.4AU) and the 4×2min (3.3±1.4AU), although no difference in mean HR or physical measures via GPS analysis between SSGs was evident. From the technical perspective, only goals scored reached significance, with post hoc analysis identifying the number of goals scored were significantly higher during the 4×2min and 2×4min SSGs compared to 8min continuous block. These results show that subjective ratings of exertion differed between conditions, but only minor technical manipulations were observed by adjusting work to rest ratios, with no significant effect on physical performance.