The Influence of Strength Level on Handball-Specific Fitness Elements Between Stronger and Weaker Professional Players

ABSTRACT

Kyriacou-Rossi, A, Hadjicharalambous, M, and Zaras, N. The influence of strength level on handball-specific fitness elements between stronger and weaker professional players. J Strength Cond Res 38(5): 966-975, 2024-The aim of the study was to investigate the influence of strength level between stronger and weaker handball players on handball specific fitness elements and to explore the correlations between strength and sport-specific fitness elements. Twenty-one professional male handball-players (age: 25.9 ± 6.9 years; mass: 87.9 ± 13.9 kg; height: 1.81 ± 0.08 m), participated in the study. Players were divided into the stronger (SG) and weaker group (WG) according to their relative to body mass 1 repetition maximum strength (1RM). Measurements included body composition, countermovement jump (CMJ), isometric leg extension peak torque (IPT) and rate of torque development (RTD), 5-step long-jump, 0-20 m linear sprint, T-half test, throwing velocity, and 1RM in bench press and squat. No significant difference was found for body composition between SG and WG ( p > 0.05). However, SG had significantly higher CMJ height (21.5%, p = 0.002), IPT (22.4%, p = 0.008), RTD relative to body mass ( p < 0.05), 5-step long jump (10.9%, p = 0.005), lower 0-20 linear sprint (-6.3%, p = 0.012), lower T-half test time trial (-7.3%, p = 0.001), and higher throwing velocity compared with WG ( p < 0.05). When all players included in one group, large to very large correlations were found between 1RM strength and IPT with fat-free mass ( r = 0.518-0.774) and throwing velocity ( r = 0.472-0.819). Very large correlations were found between RTD with fat-free mass ( r = 0.760) and throwing velocity ( r = 0.780-0.835). Stronger players have greater performance in all handball-fitness attributes compared with their weaker counterparts. The significant correlations between handball-specific fitness elements with strength and RTD suggest that strength training is essential for handball players as it may link to higher on court performance.

Reactive Strength Index, Rate of Torque Development, and Performance in Well-Trained Weightlifters: A Pilot Study

The purpose of this study was to investigate the correlation between the reactive strength index (RSI) using the drop jump (DJ) and the isometric rate of torque development (RTD) with weightlifting performance in national-level weightlifters. Seven male weightlifters (age: 28.3 ± 5.7 years, body mass: 80.5 ± 6.7 kg, body height: 1.73 ± 0.07 m) participated in this study. Measurements were performed 2 weeks prior to the national championship and included the countermovement jump (CMJ), the squat jump (SJ), the DJ from three different drop heights (20, 30, and 40 cm), and the isometric peak torque (IPT) and RTD. Performance in CMJ and SJ was significantly correlated with weightlifting performance (r ranging from 0.756 to 0.892). Significant correlations were found between weightlifting performance with DJ contact time (r ranging from -0.759 to -0.899) and RSI (r ranging from 0.790 to 0.922). Moreover, the best RSI was significantly correlated with the snatch (r = 0.921, p = 0.003) and total performance (r = 0.832, p = 0.020). Small to very large correlations were found between IPT and RTD with weightlifting performance (r ranging from 0.254 to 0.796). These results suggest that RSI and contact time variables from DJ may predict weightlifting performance in well-trained weightlifters. Additionally, IPT and RTD may provide useful insights into the neuromuscular fitness condition of the weightlifter.

Pilates-mat training and detraining: Effects on body composition and physical fitness in pilates-trained women

INTRODUCTION

Pilates-mat is an effective training method to enhance several physiological and fitness parameters, although the effects of pilates-mat detraining on body composition and physical fitness remains largely unknown. The purpose of the study was to investigate the effect of pilates-mat training and detraining on body composition and physical fitness in pilates-trained females.

METHODS

Twenty females (age: 45.1 ± 8.7 years) followed an 8-week pilates-mat training program followed by a 3-week detraining period. Measurements performed at the beginning of the training intervention, at the end of the 8-week training program and at the end of the 3-week detraining period and included: anthropometric characteristics, body composition analysis, thigh, hip and waist circumferences, blood pressure, heart rate at rest (HRr), maximum handgrip strength, abdominal curls, lower body flexibility and aerobic capacity.

RESULTS

Pilates-mat training significantly decreased body fat percentage (BF%), visceral fat and HRr (p < 0.05) but these variables returned to baseline after detraining. Trunk fat, thigh and waist circumferences decreased significantly after training and remained significantly low following detraining (p < 0.05). Abdominal curls, lower body flexibility and aerobic capacity increased significantly following pilates-mat training and remained unchanged after detraining (p < 0.05).

CONCLUSIONS

These results suggest that 8 weeks of pilates-mat training enhanced body composition and physical fitness and these physiological and physical fitness benefits were remained unaltered during the 3-week of pilates-mat detraining period. However, BF% and visceral fat returned to baseline levels following the detraining period suggesting that for maintaining the reduction in BF% and visceral fat a long-period of pilates-mat detraining should be avoided.

Higher and lower caffeine consumers: exercise performance and biological responses during a simulated soccer-game protocol following caffeine ingestion

PURPOSE

Research on whether caffeine habituation reduces its ergogenicity is scarce and conflicting. The purpose of the present study was to examine the influence of habitual caffeine consumption on exercise performance and biological responses during a simulated soccer-game protocol following acute caffeine ingestion.

METHODS

Twenty professional male soccer players were categorized as higher (n = 9) or lower caffeine consumers (n = 11) after answering a validated questionnaire. Participants performed a simulated treadmill soccer-game protocol on treadmill following either caffeine (6 mg kg^-1) or placebo ingestion, during which several variables were evaluated.

RESULTS

Time to exhaustion, countermovement jump height, mean arterial pressure, heart rate, plasma glucose, and lactate were higher (P ≤ 0.001), while rating of perceived exertion (RPE) was lower (P = 0.002), following caffeine compared to placebo ingestion, with no differences between groups (P > 0.05). Plasma non-esterified fatty acids exhibited a higher response to caffeine in the higher vs lower caffeine consumers. Reaction time, plasma glycerol and epinephrine, carbohydrate and fat oxidation, and energy expenditure were not affected by caffeine (P > 0.05).

CONCLUSION

Caffeine ingestion largely improved cardiovascular and neuromuscular performance, while reducing RPE, in both higher and lower caffeine consuming athletes during prolonged intermitted exercise to exhaustion.

The effects of moderate alterations in adrenergic activity on acute appetite regulation in obese women: A randomised crossover trial

Background:

Previous evidence has demonstrated that serum leptin is correlated with appetite in combination with, but not without, modest exercise.

Aim:

The present experiments investigated the effects of exogenous adrenaline and α/β adrenoceptor blockade in combination with moderate exercise on serum leptin concentrations, appetite/satiety sensations and subsequent food intake in obese women.

Methods:

A total of 10 obese women ((mean ± SEM), age: 50 (1.9) years, body mass index 36 (4.1) kg/m², waist 104.8 (4.1) cm) participated in two separate, double-blind randomised experimental trials. Experiment 1: moderate exercise after α/β adrenergic blocker (labetalol, 100 mg orally) versus moderate exercise plus placebo; experiment 2: adrenaline infusion for 20 minutes versus saline infusion. Appetite/satiety and biochemistry were measured at baseline, pre- and immediately post-intervention, then 1 hour post-intervention (i.e., before dinner). Food intake was assessed via ad libitum buffet-style dinner.

Results:

No differences were found in appetite/satiety, subsequent food intake or serum leptin in any of the studies (experiment 1 or experiment 2). In experiment 1, blood glucose was higher (p < 0.01) and plasma free fatty acids lower (p = 0.04) versus placebo. In experiment 2, plasma free fatty acids (p < 0.05) increased after adrenaline versus saline infusion.

Conclusions:

Neither inhibition of exercise-induced adrenergic activity by combined α/β adrenergic blockade nor moderate increases in adrenergic activity induced by intravenous adrenaline infusion affected acute appetite regulation.

Caffeine supplementation is ergogenic in soccer players independent of cardiorespiratory or neuromuscular fitness levels

Background

Equivocal findings examining the influence of caffeine on performance and biological responses to exercise may be due to inter-individual variability in cardiorespiratory or neuromuscular fitness. This study examined whether the effects of caffeine ingestion on exercise performance and biological responses to prolonged intermittent exercise to exhaustion depend on cardiorespiratory or neuromuscular fitness.

Methods

Twenty male soccer players, separated according to either cardiorespiratory fitness (high vs medium) or neuromuscular fitness (high vs medium) underwent two trials simulating the cardiovascular demands of a soccer game to exhaustion on treadmill after ingesting either caffeine (6 mg∙kg^− 1) or placebo. Physical performance, cardiorespiratory and metabolic parameters and blood metabolites were evaluated.

Results

Time to exhaustion (719 ± 288 vs 469 ± 228 s), jump height (42.7 ± 4.2 vs 38.6 ± 4.4 cm), heart rate (163 ± 12 vs 157 ± 13 b∙min^− 1), mean arterial blood pressure (98 ± 8 vs 92 ± 10 mmHg), plasma glucose (5.6 ± 0.7 vs 5.3 ± 0.6 mmol∙l^− 1) and lactate (3.3 ± 1.2 vs 2.9 ± 1.2 mmol∙l^− 1) were higher, while rating of perceived exertion (12.6 ± 1.7 vs 13.3 ± 1.6) was lower with caffeine vs placebo (p < 0.01), independent of cardiorespiratory or neuromuscular fitness level. Reaction time; plasma glycerol, non-esterified fatty acids and epinephrine; carbohydrate and fat oxidation rates; and energy expenditure were not affected by caffeine (p > 0.05).

Conclusions

Caffeine was effective in improving endurance and neuromuscular performance in athletes with either high or medium cardiorespiratory and neuromuscular fitness. Cardiorespiratory and neuromuscular fitness do not appear to modulate the ergogenic effects of caffeine supplementation in well-trained athletes.

Lean Body Mass, Muscle Architecture, and Performance in Well-Trained Female Weightlifters

Lean mass and quadriceps muscle architecture have been associated with performance in male well-trained weightlifters, but no data exist for female weightlifters. The aim of the study is to investigate the relationship between lean mass, quadriceps cross sectional area (CSA), and muscle architecture with weightlifting performance in female weightlifters. Eight well-trained female weightlifters (age 23.5 ± 6.3 years, maximum total lifting performance = 147.4 ± 34.1 kg) participated in the study. Five of the athletes were members of the national team and three were among the nation's top-five performers of the respective body-weight category. Measurements included maximum lifting performance in snatch and clean and jerk, body composition (dual x-ray absorptiometry), vastus lateralis (VL) muscle architecture, vastus intermedius (VI) muscle thickness and quadriceps muscles' CSA and countermovement jump (CMJ). Very large to nearly perfect correlations were found between snatch and clean and jerk for trunk lean body mass (r = 0.959 and 0.929), for total CSA (r = 0.732 and 0.608), and CMJ power (r = 0.933 and 0.896). These results suggest that lean body mass, quadriceps' CSA and CMJ should be monitored regularly in female weightlifters to detect potential modifications in lifting performance.

Effect of opposition quality and match location on the positional demands of the 4-2-3-1 formation in elite soccer

Background/Objective

The present study examined the influence of match location, quality of opposition team, and playing position on physical performance indicators of the 4-2-3-1 formation.

Methods

Twenty-six (n = 26) games (with 184 player-observations; n = 17 players, played full 90 min games) were recorded with a video system and the physical demands of the players were analyzed according to their specific playing position (classified into central and wide defenders, central and wide midfielders and forwards). Match performance variables analyzed included total distance (TD), high-intensity running (HIR), very-high-intensity running (VHIR) and sprinting (SPR).

Results

There was a main effect of position for TD (F = 37.84, p < 0.001), HIR (F = 41.19, p < 0.001), VHIR (F = 27.89, p < 0.001) and SPR (F = 22.25, p < 0.001). Wide defenders covered the most SPR and -along with the central midfielders-the most VHIR. Central midfielders covered the most TD and HIR. Match location and opposition quality had interactive effects on TD (F = 12.96, p < 0.001), HIR (F = 8.33 p = 0.004) and VHIR (F = 8.17 p = 0.005). Competing against "weak" opponents, more TD, HIR and VHIR covered during home games compared to away games (p < 0.05). However, more TD was covered during away games against "strong" opponents compared to away games against "weak" opponents (p < 0.05).

Conclusions

The current study supports more intense-based drills (i.e. repeated sprint training) for wide defenders and more volume-based drills (i.e. long interval training) for central midfielders, whilst total weekly training load can be adjusted based on match location and quality of oppositions on the anticipated game-load.

Effects of high-intensity interval training frequency on perceptual responses and future physical activity participation

The effectiveness of high-intensity interval training (HIIT) in inducing positive physiological adaptations is well documented. However, its impact on perceptual responses and on future physical activity (PA) engagement is less evaluated. The present study aimed to examine the effects of HIIT frequency on perceptual responses, health-related quality of life (HRQOL), and its influence in future PA participation. Thirty-five inactive adults were randomly assigned to a control (CON) and to 2 training groups that performed HIIT (10 × 60 s cycling, ∼83% peak power output) for 2 (HIIT-2) or 3 (HIIT-3) times per week for 8 weeks. Following the HIIT intervention, exercise enjoyment, HRQOL, and the intention to implement HIIT in the future were evaluated. Eight weeks after cessation of training, follow-up evaluations of HRQOL and PA were performed. Following the intervention, both training frequencies induced high levels of enjoyment (HIIT-2: 6.0 ± 1.1, HIIT-3: 6.0 ± 1.1, scale 1-7), improved HRQOL (HIIT-2: p = 0.040; HIIT-3: p = 0.024), and reported intention to implement HIIT in the future (HIIT-3: 100%, HIIT-2: 93% of participants). At follow-up, HIIT-3 participants reported higher completion of HIIT compared with HIIT-2 and CON (p < 0.05). Both training groups sustained improved HRQOL and increased vigorous and total PA (p < 0.05). This study showed that performing HIIT either 2 or 3 times per week is an enjoyable exercise modality that promotes a sustainable increase in habitual PA levels and improves HRQOL. Moreover, the higher training frequency resulted in greater HIIT completion in the 8-week period following the cessation of training.

Aerobic Fitness of Starter and Non-Starter Soccer Players in the Champion's League

To identify individual response patterns in selected aerobic fitness variables of regular starters (ST; N = 7) and non-starters (Non-ST; N = 10), top level professional soccer players were tested for maximal oxygen uptake (VO2max), velocity at 4 mM of lactate (V4), velocity at maximal oxygen uptake (νVO_2max) and oxygen pulse (O₂-pulse) in July and December following consecutive periods of fixture congestion. V4 was the only variable that increased significantly in December compared to July (15.1 ± 0.5 vs. 14.6 ± 0.5, p = 0.001). There was an almost certain beneficial large mean team change for V4 (ES = 1.2 (0.67; 1.57), 100/0/0), while beneficial mean team changes were less likely for νVO2max and O₂-pulse [ES = 0.31 (-0.08; 0.70), 68/30/2 and ES = 0.24 (0.01; 0.49), 64/36/0, respectively] and unclear for VO_2max (ES = 0.02 (-0.31; 0.70), 18/69/13). With the exception of V4 where 10 out of 17 players (7 ST and 3 Non-ST) showed positive changes higher than the biological variability, all other variables were characterized by a substantial proportion of changes lower than the biological variability. The present study demonstrated that aerobic fitness variables that require maximal effort may be characterized by greater variability of the individual response pattern compared to that of submaximal aerobic fitness variables irrespective of the accumulated game time. Submaximal aerobic fitness variables appear to be more informative in the physiological evaluation of top level soccer players and this may be an advantage during exposure to periods of consecutive games.

High-intensity Interval Training Frequency: Cardiometabolic Effects and Quality of Life

The effects of high intensity interval training (HIIT) frequency on cardiometabolic health and quality of life were examined in 35 healthy inactive adults (age: 31.7±2.6 yrs, VO₂peak: 32.7±7.4 ml·: kg^-1 ·: min^-1). Participants were randomly assigned to a control (CON) and two training groups, which performed 10×60-s cycling at ~83% of peak power, two (HIIT-2) or three times per week (HIIT-3) for eight weeks. Compared with CON, both training regimes resulted in similar improvements in VO₂peak (HIIT-2: 10.8%, p=0.048, HIIT-3: 13.6%, p=0.017), waist circumference (HIIT-2: -1.4 cm, p=0.048, HIIT-3: -2.4 cm, p=0.028), thigh cross-sectional area (HIIT-2: 11.4 cm², p=0.001, HIIT-3: 9.3 cm², p=0.001) and the physical health component of quality of life (HIIT-2: 8.4, p=0.001, HIIT-3: 12.2, p=0.001). However, HIIT-3 conferred additional health-related benefits by reducing total body and trunk fat percentage (p<0.05, compared with CON), total cholesterol and low-density lipoprotein-cholesterol (p<0.02, compared with CON) and by improving the mental component of quality of life (p=0.045, compared with CON). In conclusion, performing HIIT only twice per week is effective in promoting cardiometabolic health-related adaptations and quality of life in inactive adults. However, higher HIIT frequency is required for an effect on fat deposits, cholesterol and mental component of well-being.

An eight week school-based intervention with circuit training improves physical fitness and reduces body fat in male adolescents

BACKGORUND

School-based intervention programs have been found to effectively improve various fitness and health parameters. However, only few studies so far examined the effect of circuit training in school environment during physical education (PE) classes. The aim of the current study was to examine the effects of an eight-week circuit training on physical fitness and body fat in male adolescents.

METHODS

Thirty nine, 16-year old male high-school students participated in the current study. The students were randomly assigned to intervention and control groups. The intervention period lasted eight weeks and consisted of two circuit training sessions per week performed during regular PE classes. Total body fat was calculated by using bioelectrical impedance analysis. Physical fitness parameters such as cardiorespiratory fitness, flexibility, jumping ability and isometric arm strength were assessed through a battery of field tests. Finally, resting heart rate and blood pressure levels were assessed with an automatic monitor.

RESULTS

By the end of the intervention period, total body fat and resting systolic blood pressure were significantly lower while cardiorespiratory fitness was significantly improved in the circuit training group only (P<0.05). In the control group Body Mass Index and total body fat percentage were significantly increased when compared pre- and post-intervention period (P<0.05).

CONCLUSIONS

Eight weeks of circuit training during PE classes appeared to be effective in improving various physical fitness parameters and reducing fatness in male adolescents.

The effects of regular supplementary flexibility training on physical fitness performance of young high-level soccer players

BACKGROUND

The present study examined the effect of regular static flexibility training on selective physical fitness components in young high-level soccer-players.

METHODS

Twenty three players (mean±SD) were randomly assigned into flexibility (Flex) and control (Con) groups (Flex group: N.=12, age 16.1±0.6 years; height 1.71±.06 m; body mass 62.4±7.5 kg; peak oxygen uptake [V̇O2peak] 55.8±4.1 ml.kg-1.min-1; Con group: N.=11, age 15.9±0.6 years; height 1.73±.07 m; body mass 61.5±5.6 kg; V̇O2peak 54.2±5.2 mL.kg-1.min-1). The Flex group performed a specific static stretching training-program before and after each training session, for four weeks (4 days/week). The two groups performed two series of anthropometrics and physical-fitness tests prior to and following the application of the stretching training performed on the Flex group.

RESULTS

There were initially no main treatment effects on aerobic capacity (V̇O2peak), on 10-m sprint and on Broad-jump. However, sit-and-reach flexibility, 35m sprint and agility (P<0.05) performance, and when results corrected with Δ (magnitude of changes), Δ flexibility, Δ 35m-sprint, Δ agility and Δ Broad jump (P<.05) scores were significantly improved in Flex group compared with Con group.

CONCLUSIONS

The present results suggest that regular specific supplementary application of static stretching training is effective in improving flexibility, 35-m speed, explosiveness and agility performance in young high-level soccer-players.

Eight weeks of a combination of high intensity interval training and conventional training reduce visceral adiposity and improve physical fitness: a group-based intervention

BACKGROUND

High intensity interval training (HIIT) has been recently promoted as an effective, low volume and time-efficient training method for improving fitness and health related parameters. The aim of the current study was to examine the effect of a combination of a group-based HIIT and conventional gym training on physical fitness and body composition parameters in healthy adults.

METHODS

Thirty nine healthy adults volunteered to participate in this eight-week intervention study. Twenty three participants performed regular gym training 4 days a week (C group), whereas the remaining 16 participants engaged twice a week in HIIT and twice in regular gym training (HIIT-C group) as the other group. Total body fat and visceral adiposity levels were calculated using bioelectrical impedance analysis. Physical fitness parameters such as cardiorespiratory fitness, speed, lower limb explosiveness, flexibility and isometric arm strength were assessed through a battery of field tests.

RESULTS

Both exercise programs were effective in reducing total body fat and visceral adiposity (P<0.05) and improving handgrip strength, sprint time, jumping ability and flexibility (P<0.05) whilst only the combination of HIIT and conventional training improved cardiorespiratory fitness levels (P<0.05). A between of group changes analysis revealed that HIIT-C resulted in significantly greater reduction in both abdominal girth and visceral adiposity compared with conventional training (P<0.05).

CONCLUSIONS

Eight weeks of combined group-based HIIT and conventional training improve various physical fitness parameters and reduce both total and visceral fat levels. This type of training was also found to be superior compared with conventional exercise training alone in terms of reducing more visceral adiposity levels. Group-based HIIT may consider as a good methods for individuals who exercise in gyms and craving to acquire significant fitness benefits in relatively short period of time.

The relationship between physical fitness and obesity among a sample of adolescents in Cyprus

Recent data revealed that adolescent obesity appeared to be a rising problem in Cyprus. However, there is a scarcity of published data regarding fitness-related parameters, which could contribute for the presence of obesity in Cyprus' adolescence population. The aim of the current study was to investigate the association between adolescent obesity, body composition, and fitness levels. A total of 270 high school students volunteered to participate in this cross-sectional study. Body mass and height were assessed in order to calculate body mass index, while body fat percentage was calculated by using bioelectrical impedance analysis. Physical fitness parameters were assessed through a battery of field tests. Body fat was inversely associated with cardiorespiratory fitness levels, sprint and jumping performance, as well as with the frequency of physical education class sessions per week (p<0.05). The adolescents with high body fat were found to exhibit significant reductions in all the fitness related parameters (p<0.05), except with the arm strength (p>0.05). This study is the first to uncover an inverse association between high body fat and fitness-related parameters among a sample of adolescents in Cyprus. These data can be used in order to develop effective interventions aiming to counterbalance obesity and improve the overall health and the quality of life of adolescents.

Brain serotonin and dopamine modulators, perceptual responses and endurance performance during exercise in the heat following creatine supplementation

BACKGROUND

The present experiment examined the responses of peripheral modulators and indices of brain serotonin (5-HT) and dopamine (DA) function and their association with perception of effort during prolonged exercise in the heat after creatine (Cr) supplementation.

METHODS

Twenty one endurance-trained males performed, in a double-blind fashion, two constant-load exercise tests to exhaustion at 63 +/- 5% V(O2) max in the heat (ambient temperature: 30.3 +/- 0.5 degrees C, relative humidity: 70 +/- 2%) before and after 7 days of Cr (20 g.d-1 Cr + 140 g.d-1 glucose polymer) or placebo (Plc) (160 g.d-1 glucose polymer) supplementation.

RESULTS

3-way interaction has shown that Cr supplementation reduced rectal temperature, heart rate, ratings of perceived leg fatigue (P < 0.05), plasma free-tryptophan (Trp) (P < 0.01) and free-Trp:tyrosine ratio (P < 0.01) but did not influence the ratio of free-Trp:large neutral amino acids or contribute in improving endurance performance (Plc group, n = 10: 50.4 +/- 8.4 min vs. 51.2 +/- 8.0 min, P > 0.05; Cr group, n = 11: 47.0 +/- 4.7 min vs. 49.7 +/- 7.5 min, P > 0.05). However, after dividing the participants into "responders" and "non-responders" to Cr, based on their intramuscular Cr uptake, performance was higher in the "responders" relative to "non-responders" group (51.7 +/- 7.4 min vs.47.3 +/- 4.9 min, p < 0.05).

CONCLUSION

Although Cr influenced key modulators of brain 5-HT and DA function and reduced various thermophysiological parameters which all may have contributed to the reduced effort perception during exercise in the heat, performance was improved only in the "responders" to Cr supplementation. The present results may also suggest the demanding of the pre-experimental identification of the participants into "responders" and "non-responders" to Cr supplementation before performing the main experimentation. Otherwise, the possibility of the type II error may be enhanced.

Influence of caffeine on perception of effort, metabolism and exercise performance following a high-fat meal

This study examined the effects of caffeine, co-ingested with a high fat meal, on perceptual and metabolic responses during incremental (Experiment 1) and endurance (Experiment 2) exercise performance. Trained participants performed three constant-load cycling tests at approximately 73% of maximal oxygen uptake (VO2max) for 30 min at 20 degrees C (Experiment 1, n = 8) and to the limit of tolerance at 10 degrees C (Experiment 2, n = 10). The 30 min constant-load exercise in Experiment 1 was followed by incremental exercise (15 W . min-1) to fatigue. Four hours before the first test, the participants consumed a 90% carbohydrate meal (control trial); in the remaining two tests, the participants consumed a 90% fat meal with (fat + caffeine trial) and without (fat-only trial) caffeine. Caffeine and placebo were randomly assigned and ingested 1 h before exercise. In both experiments, ratings of perceived leg exertion were significantly lower during the fat + caffeine than fat-only trial (Experiment 1: P < 0.001; Experiment 2: P < 0.01). Ratings of perceived breathlessness were significantly lower in Experiment 1 (P < 0.01) and heart rate higher in Experiment 2 (P < 0.001) on the fat + caffeine than fat-only trial. In the two experiments, oxygen uptake, ventilation, blood [glucose], [lactate] and plasma [glycerol] were significantly higher on the fat + caffeine than fat-only trial. In Experiment 2, plasma [free fatty acids], blood [pyruvate] and the [lactate]:[pyruvate] ratio were significantly higher on the fat + caffeine than fat-only trial. Time to exhaustion during incremental exercise (Experiment 1: control: 4.9, s = 1.8 min; fat-only: 5.0, s = 2.2 min; fat + caffeine: 5.0, s = 2.2 min; P > 0.05) and constant-load exercise (Experiment 2: control: 116 (88 - 145) min; fat-only: 122 (96 - 144) min; fat + caffeine: 127 (107 - 176) min; P > 0.05) was not different between the fat-only and fat + caffeine trials. In conclusion, while a number of metabolic responses were increased during exercise after caffeine ingestion, perception of effort was reduced and this may be attributed to the direct stimulatory effect of caffeine on the central nervous system. However, this caffeine-induced reduction in effort perception did not improve exercise performance.

Chronic fatigue syndrome: new evidence for a central fatigue disorder

Considerable evidence points towards a prominent role for central nervous system (CNS) mechanisms in the pathogenesis of chronic fatigue syndrome (CFS), a disorder characterized chiefly by persistent, often debilitating, fatigue. We wished to characterize circulating profiles of putative amino acid modulators of CNS 5-hydroxytryptamine (5-HT; serotoninergic) and dopaminergic function in CFS patients at rest, as well as during symptom-limited exercise and subsequent recovery. Groups of 12 CFS patients and 11 age- and sex-matched sedentary controls, with similar physical activity histories, underwent ramp-incremental exercise to the limit of tolerance. Plasma amino acid concentrations, oxygen uptake and ratings of perceived exertion were measured at rest, and during exercise and recovery. Peak oxygen uptake was significantly lower in the CFS patients compared with controls. Rating of perceived exertion in the patients was higher at all time points measured, including at rest, relative to controls. Levels of free tryptophan (free Trp), the rate-limiting 5-HT precursor, were significantly higher in CFS patients at exhaustion and during recovery, whereas concentrations of branched-chain amino acids (BCAA) and large neutral amino acids (LNAA) were lower in CFS patients at exhaustion, and for LNAA also during recovery. Consequently, the [free Trp]/[BCAA] and [free Trp]/[LNAA] ratios were significantly higher in CFS patients, except at rest. On the other hand, levels of tyrosine, the rate-limiting dopaminergic precursor, were significantly lower at all time points in the CFS patients. The significant differences observed in a number of key putative CNS 5-HT and dopaminergic modulators, coupled with the exacerbated perception of effort, provide further evidence for a potentially significant role for CNS mechanisms in the pathogenesis of CFS.