Motocross is one of the most popular high-speed motorcycle races, which takes place on a naturally closed track with significant challenges. This study aimed to characterize anthropometric, circulatory, and lower and upper limb muscle properties based on laboratory and race-recorded characteristics. Male competitors (n = 3) aged 14 years (MX) were included in the study. All three boys have national and international experience. Metabolic characteristics (ventilation, oxygen consumption, and carbon dioxide production) and heart rate (HR) were measured in the laboratory while HR and speed were measured while racing. No significant difference was found between the three competitors in terms of HR during the race. In terms of number of sprints (No. sprint) and maximum speed (Speedmax), we found the most successful runner (highest finisher) to have the most sprints and maximum speed. Comparing the metabolic characteristics, it was found that racing was between the respiratory breakpoint (VT1) and the respiratory compensation point (RCP), but, in several cases, crossed the anaerobic threshold. While motocross riders are exposed to extreme conditions and high physical demands, in motorsport, victories depend not only on the athlete’s physical abilities but also on several factors such as driving technique, mental effort, equipment efficiency and resistance, race strategy, and team competence.

Background: Motocross riders’ performance is highly dependent on the characteristics of the motorcycles and the skills of the riders, and the actual environmental conditions. This study aims to describe the differences in anthropometric and physiological characteristics between internationally ranked adolescent males and nationally ranked motorcross (MX) peer competitors; Methods: Data obtained from young riders (n=14) were divided into internationally ranked G1 (n=5) and - nationally ranked G2 (n=9) young MX riders. We determined body composition and cardiorespiratory variables, and measured heart rate and movement-related data with Polar Team Pro system during the race; (3) Results: Blood lactate concentrations were evaluated before and after the race session. MX riders with an international ranking performed significantly better during both races (R1 and R2), which manifested itself in significantly shorter times per lap on average (difference for R1=14.8 s and for R2=16.7 s, respectively, p=0.017), more laps completed (G1 vs G2 approx.: 11.2: 9.9 laps for R1 and R2, p=0.019) and points scored (difference: R1=9.3 pts and R2=9.0 pts, p=0.014). There were no statistically significant differences in age between the two compared groups (p=0.559) and other anthropometric and physiological characteristics tested, with an exception of muscle mass percent (p<0.001); Conclusions: Current results showed that motocross probably places a heavy burden on riders, who need to be fit enough to maintain their position in the field.

BACKGROUNDː The literature provides relatively few and incomplete studies on comparisons of body composition measurement procedures, especially when related to sport experience, gender and age. The purpose of this study was to compare and contrast the applicability of the bioelectric impedance (BIA) and the fourcomponent anthropometry (Drinkwater-Ross) methods among young athletes. METHODSː 142 school-aged competitive athletes (nmale=71; nfemale=71, Mage=11.72±2.33) from a suburb in Hungary participated in the study. Data collection included standard Drinkwater-Ross anthropometric fractionation (bone mass, muscle and fat mass, and residual mass, estimated by equations) and bioelectrical impedance analysis with measured muscle mass (SMM_Inbody) and body fat percentage (PBF%Inbody) methods. In order to better understand the higher standard correlations of the methods, Parízkova percentage of body fat (Parízkova BF%) was also included in the analysis. Data analysis was performed by gender and age range. RESULTSː According to the data, it seems that the muscle mass estimated by BIA (SMM Inbody) is higher than the Drinkwater-Ross estimation (eMM) both in males and females and in each age-group. Also, muscle mass is overestimated, meanwhile body fat% (PBF% Inbody) is underestimated by BIA compared to Parízkova BF%. However, our results show significant correlations (0.60.9, p<.001) between estimated fat mass and muscle mass in all cases (eMM, eFM); similarly, the estimated body fat percentages in all cases were strongly correlated (Parízkova BF% and PBF% Inbody). CONCLUSIONSː Correlational analyses proved that estimation of body fat mass, muscle mass, and percentage of body fat by BIA measurement are closely associated with both Drinkwater-Ross anthropometric fractionation and Parízkova. Our findings suggest that the (BIA) predictive performance is equally appropriate as other reference techniques (e.g. Drinkwater-Ross, Parízkova) in the case of young athletes. Consequently, both the device (bioelectrical impedance device) and the ease of use of the results make for a truly user-friendly and scientifically supported procedure.

Intense exercise by top-level athletes significantly lowers the pH of muscle and blood, which leads to fatigue. Beta-alanine (BA) supplementation can increase carnosine levels in skeletal muscle, which can delay a decrease in pH in the muscles. Previous studies have shown that multiple doses of BA supplementation were effective for people of different physical fitness and age. The purpose of this double-blind, randomized, controlled study is to investigate the effect of a five-week BA supplementation on well-trained, experienced rowing athletes at approximately the median dose of previous studies, which determined that 50 mg day⁻¹ kg⁻¹ of body weight was an effective daily dose. Two groups were formed in the spiroergometric study. One group received BA supplementation, while the control group did not. Five weeks after the first test (T1), the second test (T2) occurred, and the blood lactate levels were measured before and after the tests (Pre[La-]b; Post[La-]b). The maximum mean values of different physiological load parameters showed no significant difference. In the BA group, the mean lactate level was significantly lower after the T2 measurement (Post[La-]b) compared to those of T1 (P = 0.01) and the control group, i.e., T1 (P = 0,008), T2 (P = 0,028). The mean time and performance of the second measurement of the BA group increased [T1 = 582,7 ± 88,2 (s); T2 = 636,4 ± 106,6 (s)] but the result is not significant. In summary, the five-week dose of 50 mg day⁻¹ kg⁻¹ of body weight, which is 3.845 day⁻¹ for the group average, lowers the blood lactate levels after the tests (Post[La-]b) but does not increase the athlete's performance. For well-trained athletes, during a five-week supplementation, it is not advisable to lover the value below 4–6 g day⁻¹ with the dietary supplement to achieve an ergogenic effect.