Acute carnosine and ß-alanine supplementation increase the compensated part of the ventilation versus work rate relationship during a ramp incremental cycle test in physically active men.

BACKGROUND: Chronic supplementation with carnosine and ß-alanine (Carn-ßA) has been proposed to improve muscle contractility and reduce muscle fatigue mainly through an increase in intracellular pH buffering capacity. However, the acute ergogenic effects of Carn-ßA supplementation are poorly investigated. This study aimed at evaluating the acute effects of a single Carn-ßA supplementation on the cardiorespiratory and metabolic response during a ramp cycle-ergometric test. METHODS: This randomized, double-blind, placebo-controlled study, involved 10 healthy males (age: 22.2±1.9 years, body mass: 72.5±7.9 kg, stature: 1.72±0.08 m, Body Mass Index: 24.47±1.91 kg/m2, mean±standard deviation). All the participants performed two maximal incremental ramp tests on a cycle ergometer, with a prior randomized assumption of 2.5 g L-carnosine plus 2.5 g ß-alanine (Carn-ßA) or placebo (PLA). During exercise, gas exchange parameters were measured breath-by-breath, heart rate was monitored by electrocardiography and rate perceived exertion was determined on Borg scales. From the ramp test, peak cardiorespiratory and metabolic parameters and ventilatory thresholds (VT1 and VT2) were calculated offline. RESULTS: No differences between the experimental conditions emerged at peak exercise. However, despite acute Carn-ßA supplementation did not affect the single ventilatory thresholds, the compensated portion of the ramp test (i.e. the difference between VT2 and VT1) was significantly larger (P=0.043) in Carn-ßA. CONCLUSIONS: These findings demonstrate a positive effect of acute Carn-ßA supplementation on the compensated part of the exercise. This should be taken into account by nutritionists and athletes searching for nutritional supplements, when a quick effect based on an acute dose is required.

Physiological and technical commitment during a 300-m in-line skating trial in athletes of different age categories.

BACKGROUND: This study investigated the differences in strength, technique and time performance in in-line skaters of three age categories during a 300-meter trial. Possible correlations among these variables were also assessed. METHODS: Thirty-six elite in-line skaters (Cadets, Juniors and Seniors, N.=12 each; 14±1, 16±1, and 24±6 years of age, respectively) performed a 300-m trial on an outdoor oval track. Total time (Ttot), 100-m fractions and duration of each skating technique (initial acceleration phase, straight push and cross-over) were recorded. A squat jump (SJ) was performed before and after the trial. Heart rate, blood lactate concentration ([La-]) and rate of perceived exertion (RPE) were collected before, during and at the end of the trial. RESULTS: Ttot was longer and SJ lower in Cadets compared to the other groups. Seniors employed the cross-over technique for a longer period than the straight push technique, compared to Juniors and Cadets. Ttot correlated negatively with SJ in Seniors. The number of significant correlations between skating techniques' duration and both Ttot and SJ increased with age category. No differences among groups were found for heart rate, [La-] and RPE. CONCLUSIONS: With increasing age category, leg strength appeared to be the more related aspect to skating performance. To improve 300-m in-line skating performance, trainers should pay particular attention to the enhancement of leg strength and cross-over skating technique.

Kayaking performance is altered in mentally fatigued young elite athletes.

BACKGROUND: The present study aimed to assess the impact of 60 min of a cognitive demanding task inducing mental fatigue (Stroop) on kayaking performance in young elite athletes. The second objective was to elucidate the effect of mental fatigue on performance in a population of young under-17 elite athletes of national. METHODS: Thirteen under-17 elite kayakers completed 60 min of an incongruent Stroop color-word test, or the equivalent time in a control condition in a cross-over study design. Afterwards, participants completed a 2000 m kayaking time trial in which power output, stroke rate and time at the end of 400, 800, 1200, 1600 and 2000 m were recorded. Physiological and perceptual measures of heart rate (HR), blood lactate and rating of perceived exertion (RPE) were collected during the time trial. Psychological questionnaires were used to assess fatigue and mental demand of the Stroop. Subjective ratings of mental fatigue following the Stroop were almost certainly higher. RESULTS: Results of the time trial suggested that mental fatigue almost certainly impaired power output, stroke rate and time (552±30 s) compared to the control (521±36 s) condition. Yet, during the time trial RPE was almost certainly higher in the mental fatigue condition, while HR was reported to be possibly lower. Blood lactate resulted almost certainly lower in the mental fatigue state at completion of the time trial (10.3±1.5 vs. 12.2±1.6 mmol·L-1). CONCLUSIONS: Mental fatigue has an almost certain negative impact on 2000-m kayaking performance in young elite athletes.

Validity and reliability of submaximal fitness tests based on perceptual variables.

BACKGROUND: Few studies examined the validity of fitness tests based on perception scales. The field-based fitness tests batteries are composed by maximal tests and currently, a battery of submaximal tests does not exist. METHODS: Seventeen physically active male participants (age 40.5±10.7 years) performed the Multistage Fitness Test, the Crunch Test, the Push-Up Test and a Trunk Flexion Test with a submaximal protocol based on perceptual variables that were defined as non-validated submaximal. The mentioned tests were repeated three times to assess their reliability. The participants also performed four validated maximal tests comprising a velocity dependent ramp test on the treadmill, the Crunch Test, the Push-Up Test, and Sit-and-Reach Test. The submaximal tests were correlated to the maximal ones to assess their criterion validity. RESULTS: All the submaximal tests showed an ICC superior to 0.8 apart from the submaximal Crunch Test. The correlation between Maximal Treadmill Test and submaximal Multistage Fitness Test was 0.77. The correlation between Sit-and-Reach Test and submaximal Trunk Flexion Test was 0.71. Correlations equal to 0.66 and 0.60 were found between the maximal and submaximal Crunch Test and Push-Up Test respectively. CONCLUSIONS: The use of submaximal tests based on a fixed value of perception can represent a suitable tool to assess cardiorespiratory fitness and flexibility because of their correlation with the corresponding maximal evaluation tests and because of their reliability. On the contrary, muscular endurance capacity seems not to be assessable in the same manner.