There is consistent evidence supporting the ergogenic effects of caffeine for endurance based exercise. However, whether caffeine ingested through coffee has the same effects is still subject to ...debate. The primary aim of the study was to investigate the performance enhancing effects of caffeine and coffee using a time trial performance test, while also investigating the metabolic effects of caffeine and coffee. In a single-blind, crossover, randomised counter-balanced study design, eight trained male cyclists/triathletes (Mean ± SD: Age 41 ± 7 y, Height 1.80 ± 0.04 m, Weight 78.9 ± 4.1 kg, VO2 max 58 ± 3 ml • kg(-1) • min(-1)) completed 30 min of steady-state (SS) cycling at approximately 55% VO2max followed by a 45 min energy based target time trial (TT). One hour prior to exercise each athlete consumed drinks consisting of caffeine (5 mg CAF/kg BW), instant coffee (5 mg CAF/kg BW), instant decaffeinated coffee or placebo. The set workloads produced similar relative exercise intensities during the SS for all drinks, with no observed difference in carbohydrate or fat oxidation. Performance times during the TT were significantly faster (~5.0%) for both caffeine and coffee when compared to placebo and decaf (38.35 ± 1.53, 38.27 ± 1.80, 40.23 ± 1.98, 40.31 ± 1.22 min respectively, p<0.05). The significantly faster performance times were similar for both caffeine and coffee. Average power for caffeine and coffee during the TT was significantly greater when compared to placebo and decaf (294 ± 21 W, 291 ± 22 W, 277 ± 14 W, 276 ± 23 W respectively, p<0.05). No significant differences were observed between placebo and decaf during the TT. The present study illustrates that both caffeine (5 mg/kg/BW) and coffee (5 mg/kg/BW) consumed 1 h prior to exercise can improve endurance exercise performance.
Female soccer has seen a substantial rise in participation, as well as increased financial support from governing bodies over the last decade. Thus, there is an onus on researchers and medical ...departments to develop a better understanding of the physical characteristics and demands, and the health and performance needs of female soccer players. In this review, we discuss the current research, as well as the knowledge gaps, of six major topics: physical demands, talent identification, body composition, injury risk and prevention, health and nutrition. Data on female talent identification are scarce, and future studies need to elucidate the influence of relative age and maturation selection across age groups. Regarding the physical demands, more research is needed on the pattern of high-intensity sprinting during matches and the contribution of soccer-specific movements. Injuries are not uncommon in female soccer players, but targeting intrinsically modifiable factors with injury prevention programmes can reduce injury rates. The anthropometric and physical characteristics of female players are heterogeneous and setting specific targets should be discouraged in youth and sub-elite players. Menstrual cycle phase may influence performance and injury risk; however, there are few studies in soccer players. Nutrition plays a critical role in health and performance and ensuring adequate energy intake remains a priority. Despite recent progress, there is considerably less research in female than male soccer players. Many gaps in our understanding of how best to develop and manage the health and performance of female soccer players remain.
The purpose of this study was to expand our previously published sweat normative data/analysis (n = 506) to establish sport-specific normative data for whole-body sweating rate (WBSR), sweat Na
+
, ...and rate of sweat Na
+
loss (RSSL). Data from 1303 athletes were compiled from observational testing (2000-2017) using a standardized absorbent sweat patch technique to determine local sweat Na
+
and normalized to whole-body sweat Na
+
. WBSR was determined from change in exercise body mass, corrected for food/fluid intake and urine/stool loss. RSSL was the product of sweat Na
+
and WBSR. There were significant differences between sports for WBSR, with highest losses in American football (1.51 ± 0.70 L/h), then endurance (1.28 ± 0.57 L/h), followed by basketball (0.95 ± 0.42 L/h), soccer (0.94 ± 0.38 L/h) and baseball (0.83 ± 0.34 L/h). For RSSL, American football (55.9 ± 36.8 mmol/h) and endurance (51.7 ± 27.8 mmol/h) were greater than soccer (34.6 ± 19.2 mmol/h), basketball (34.5 ± 21.2 mmol/h), and baseball (27.2 ± 14.7 mmol/h). After ANCOVA, significant between-sport differences in adjusted means for WBSR and RSSL remained. In summary, due to the significant sport-specific variation in WBSR and RSSL, American football and endurance have the greatest need for deliberate hydration strategies.
Abbreviations: WBSR: whole body sweating rate; SR: sweating rate; Na
+
: sodium; RSSL: rate of sweat sodium loss
This study aimed to quantify and compare sleep architecture before and after home and away matches in elite soccer players from the English Premier League. Across two seasons, 6 male players (age 28 ...± 5 y; body mass 85.1 ± 9.5 kg; height 1.86 ± 0.09 m) wore WHOOP straps to monitor sleep across 13 matches that kicked off before 17:00 h. For each, sleep was recorded the night before (MD
), after (MD) and following the match (MD
). Across these 3 days total sleep time (TST), sleep efficiency (SE), sleep disturbances, wake time, light sleep, deep sleep, REM sleep, sleep and wake onsets, alongside external load, were compared. TST was reduced after MD versus MD
(392.9 ± 76.4 vs 459.1 ± 66.7 min,
= 0.003) but no differences existed in any other sleep variables between days (
> 0.05). TST did not differ after home (386.9 ± 75.7 min) vs. away matches (401.0 ± 78.3 min) (
= 0.475), nor did other sleep variables (
> 0.05). GPS-derived external load peaked on MD (
< 0.05). In conclusion, despite reduced TST on MD, sleep architecture was unaffected after matches played before 17:00 h, suggesting sleep quality was not significantly compromised.
INTRODUCTIONThe aim of this study was to describe maximal fat oxidation (MFO) rates in an athletic population.
METHODIn total, 1121 athletes (933 males, 188 females), from a variety of sports and ...competitive level, undertook a graded exercise test on a treadmill in a fasted state (≥5 h fasted). Rates of fat oxidation were determined using indirect calorimetry.
RESULTSAverage MFO was 0.59 ± 0.18 gBULLET OPERATORmin, ranging from 0.17 – 1.27 gBULLET OPERATORmin. Maximal rates occurred at an average exercise intensity of 49.3 ± 14.8% V˙O2max, ranging from 22.6 – 88.8% V˙O2max. In absolute terms, male athletes had significantly higher MFO compared to females (0.61 and 0.50 gBULLET OPERATORmin respectively, P < 0.001). Expressed relative to fat free mass (FFM), MFO were higher in the females compared to males (MFO/FFM11.0 and 10.0 mgBULLET OPERATORkgBULLET OPERATORFFMBULLET OPERATORmin respectively, P < 0.001). Soccer players had the highest MFO/FFM (10.8 mgBULLET OPERATORkgBULLET OPERATORFFMBULLET OPERATORmin), ranging from 4.1 – 20.5 mgBULLET OPERATORkgBULLET OPERATORFFMBULLET OPERATORmin, whereas, American Football players displayed the lowest rates of MFO/FFM (9.2 mgBULLET OPERATORkgBULLET OPERATORFFMBULLET OPERATORmin). In all athletes, and when separated by sport, large individual variations in MFO rates were observed. Significant positive correlations were found between MFO (gBULLET OPERATORmin) and the following variablesFFM, V˙O2max, FATMAX (the exercise intensity at which the MFO was observed), percent body fat (%BF) and duration of fasting. When taken together these variables account for 47% of the variation in MFO.
CONCLUSIONMFO and FATMAX vary significantly between athletes participating in different sports but also in the same sport. Although variance in MFO can be explained to some extent by body composition and fitness status, more than 50% of the variance is not explained by these variables and remains unaccounted for. KEYWORDSFat Oxidation; Athletes; Exercise Metabolism; PhysiologyThis is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially.
This study aimed to assess energy availability (EA), alongside possible risk factors of reduced or low EA of professional female soccer players during a competitive season. Thirteen players (age: ...23.7 ± 3.4 y, stature: 1.69 ± 0.08 m, body mass: 63.7 ± 7.0 kg) engaged in a 5-day (two rest days, one light training, heavy training and match day) monitoring period. Energy intake (EI) and expenditure during exercise (EEE) were measured. EA was calculated and categorised as optimal, reduced or low (>45, 30-45, <30 kcal·kg FFM
−1
·day
−1
, respectively). Relationships between EA and bone mineral density, resting metabolic rate (RMR), plasma micronutrient status, biochemical markers and survey data were assessed. EA was optimal for 15%, reduced for 62% and low for 23% of players. Higher EA was observed on rest days compared to others (P<0.05). EA was higher for the light compared to the heavy training day (P<0.001). EEE differed significantly between days (P<0.05). EI (2124 ± 444 kcal), carbohydrate (3.31 ± 0.64 g·kg·day
−1
) and protein (1.83 ± 0.41 g·kg·day
−1
) intake remained similar (P>0.05). Survey data revealed 23% scored
8 on the Low Energy Availability in Females Questionnaire and met criteria for low RMR (ratio <0.90). Relationships between EA and risk factors were inconclusive. Most players displayed reduced EA and did not alter EI or carbohydrate intake according to training or match demands. Although cases of low EA were identified, further work is needed to investigate possible long-term effects and risk factors of low and reduced EA separately to inform player recommendations.
BACKGROUND: Green tea catechins have been hypothesized to increase energy expenditure and fat oxidation by inhibiting catechol-O-methyltransferase (COMT) and thus promoting more sustained adrenergic ...stimulation. Metabolomics may help to clarify the mechanisms underlying their putative physiological effects. OBJECTIVE: The study investigated the effects of 7-day ingestion of green tea extract (GTE) on the plasma metabolite profile at rest and during exercise. METHODS: In a placebo-controlled, double-blind, randomized, parallel study, 27 healthy physically active males consumed either GTE (n=13, 1200 mg catechins, 240 mg caffeine/day) or placebo (n=14, PLA) drinks for 7 days. After consuming a final drink (day 8), they rested for 2 h and then completed 60 min of moderate-intensity cycling exercise (56%±4% VO₂max). Blood samples were collected before and during exercise. Plasma was analyzed using untargeted four-phase metabolite profiling and targeted profiling of catecholamines. RESULTS: Using the metabolomic approach, we observed that GTE did not enhance adrenergic stimulation (adrenaline and noradrenaline) during rest or exercise. At rest, GTE led to changes in metabolite concentrations related to fat metabolism (3-β-hydroxybutyrate), lipolysis (glycerol) and tricarboxylic acid cycle (TCA) cycle intermediates (citrate) when compared to PLA. GTE during exercise caused reductions in 3-β-hydroxybutyrate concentrations as well as increases in pyruvate, lactate and alanine concentrations when compared to PLA. CONCLUSIONS: GTE supplementation resulted in marked metabolic differences during rest and exercise. Yet these metabolic differences were not related to the adrenergic system, which questions the in vivo relevance of the COMT inhibition mechanism of action for GTE.
Hypohydration increases physiological strain and reduces physical and technical soccer performance, but there are limited data on how fluid balance responses change between different types of ...sessions in professional players. This study investigated sweat and fluid/carbohydrate intake responses in elite male professional soccer players training at low and high intensities in cool and hot environments. Fluid/sodium (Na
) losses and ad-libitum carbohydrate/fluid intake of fourteen elite male soccer players were measured on four occasions: cool (wet bulb globe temperature (WBGT): 15 ± 7 °C, 66 ± 6% relative humidity (RH)) low intensity (rating of perceived exertion (RPE) 2-4, m·min
40-46) (CL); cool high intensity (RPE 6-8, m·min
82-86) (CH); hot (29 ± 1 °C, 52 ± 7% RH) low intensity (HL); hot high intensity (HH). Exercise involved 65 ± 5 min of soccer-specific training. Before and after exercise, players were weighed in minimal clothing. During training, players had ad libitum access to carbohydrate beverages and water. Sweat Na
(mmol·L
), which was measured by absorbent patches positioned on the thigh, was no different between conditions, CL: 35 ± 9, CH: 38 ± 8, HL: 34 ± 70.17, HH: 38 ± 8 (
= 0.475). Exercise intensity and environmental condition significantly influenced sweat rates (L·h
), CL: 0.55 ± 0.20, CH: 0.98 ± 0.21, HL: 0.81 ± 0.17, HH: 1.43 ± 0.23 (
=0.001), and percentage dehydration (
< 0.001). Fluid intake was significantly associated with sweat rate (
= 0.019), with no players experiencing hypohydration > 2% of pre-exercise body mass. Carbohydrate intake varied between players (range 0-38 g·h
), with no difference between conditions. These descriptive data gathered on elite professional players highlight the variation in the hydration status, sweat rate, sweat Na
losses, and carbohydrate intake in response to training in cool and hot environments and at low and high exercise intensities.
Green tea is made from the leaves of the Camellia sinensis L plant, which is rich in polyphenol catechins and caffeine. There is increasing interest in the potential role of green tea extract (GTE) ...in fat metabolism and its influence on health and exercise performance. A number of studies have observed positive effects of GTE on fat metabolism at rest and during exercise, following both shorter and longer term intake. However, overall, the literature is inconclusive. The fact that not all studies observed effects may be related to differences in study designs, GTE bioavailability, and variation of the measurement (fat oxidation). In addition, the precise mechanisms of GTE in the human body that increase fat oxidation are unclear. The often-cited in vitro catechol-O-methyltransferase mechanism is used to explain the changes in substrate metabolism with little in vivo evidence to support it. Also, changes in expression of fat metabolism genes with longer term GTE intake have been implicated at rest and with exercise training, including the upregulation of fat metabolism enzyme gene expression in the skeletal muscle and downregulation of adipogenic genes in the liver. The exact molecular signaling that activates changes to fat metabolism gene expression is unclear but may be driven by PPAR-γ coactivator 1-α and PPARs. However, to date, evidence from human studies to support these adaptations is lacking. Clearly, more studies have to be performed to elucidate the effects of GTE on fat metabolism as well as improve our understanding of the underlying mechanisms.
This study examined sweat rate, sweat sodium concentration Na+, and ad-libitum carbohydrate and fluid intakes in elite female soccer players during training (n = 19) and a match (n = 8); eight ...completed both for comparisons. Body mass (kg) was obtained before and after exercise to calculate sweat rate. The sweat Na+ was determined from absorbent patches on the thigh or back. Sweat rate, percentage body mass change, and sweat Na+ for 19 players during training were 0.47 ± 0.19 L·h−1, +0.19 ± 0.65%, and 28 ± 10 mmol·L−1, respectively. Sweat rate was higher during a match (0.98 ± 0.34 L·h−1) versus training (0.49 ± 0.26 L·h−1, p = 0.007). Body mass losses were greater post-match (−1.12 ± 0.86%) than training (+0.29 ± 0.34%, p = 0.003). Sweat Na+ was similar for training (29 ± 9 mmol·L−1) and a match (35 ± 9 mmol·L−1) (p = 0.215). There were no differences in match versus training carbohydrate intakes (2.0 ± 2.3 g·h−1, 0.9 ± 1.5 g·h−1, respectively, p = 0.219) or fluid intakes (0.71 ± 0.30 L·h−1, 0.53 ± 0.21 L·h−1, respectively, p = 0.114). In conclusion, female soccer players’ sweat rates were higher during a match than during training, and carbohydrate intakes were below recommendations for matches and training.
PDF
