ECSS Paris 2023: CP-AP11
INTRODUCTION: Sprint training can be enhanced through assisted and resisted methods, which influence both sprint mechanics and overall performance. Assisted sprinting, typically involving towing mechanisms, has been studied using various towing forces, often providing constant full assistance. However, little is known about how adjusting these forces and setting specific speeds impact performance. Unlike full assistance, partial assistance reduces the towing force as the athlete approaches a certain speed, allowing for a more dynamic and adaptive sprinting experience. This method may require greater voluntary effort from the athlete, potentially leading to better training adaptations. Therefore, it was hypothesized that partial assistance sprinting would provide greater benefits compared to full assistance. METHODS: This study compared two assisted sprint training methods: fully assisted sprinting with a constant 6 kg towing force and partially assisted sprinting, where assistance diminished once the athlete approached 0.5 m/s below their supra-maximal speed. Twenty-four male youth football players (age: 17.0 ± 1.9 years, body mass: 69.7 ± 9.9 kg, height: 1.80 ± 0.06 m) participated in the study during their offseason. Eight athletes completed the fully assisted training, eight underwent partial assistance training, and the remaining participants formed a control group. The subjects were tested in both a 30-meter regular sprint and a 30-meter fully assisted sprint. The training program consisted of four 30-meter assisted sprints performed twice a week for a total of 10 sessions. A motorized device provided precise assistance loads, while sprint times were measured using the Witty Gate timing system. Maximal speed and 5-meter average speed were recorded by the towing device. Additionally, stride length, stride frequency, contact time, and flight time were analyzed using the OptoJump Next modular system. RESULTS: Thirty-meter fully assisted sprint times significantly improved in both the fully and partially assisted groups (p < 0.05 for both). Additionally, contact times during both regular 30-meter sprinting and 30-meter fully assisted sprinting were significantly reduced (p < 0.05 for both). However, regular 30-meter sprint times remained unchanged. CONCLUSION: Both fully and partially assisted sprint training methods effectively enhance 30-meter assisted sprint performance. Additionally, both methods led to a significant reduction in contact times, which may contribute to improved stride efficiency and sprint mechanics. However, longer training periods might be needed for a significant improvement in a regular 30-meter run. These results help coaches refine sprint training strategies, enabling them to adjust assistance techniques to better suit individual athletes.
Read CV Austra SkujyteECSS Paris 2023: CP-AP11
INTRODUCTION: Limited research has explored the relationship between variations in bioelectrical parameters during the full training season and the athletic performance of track and field sprinters of both genders. METHODS: We collected longitudinal anthropometric and regional bioelectrical impedance vector analysis (BIVA) measurements of 12 female (age: 23.5 ±3.7) and 9 male (age: 23.9 ±5.2) sprinters, with >6 years experience and tier 3, for 9 months of periodization (T1, general conditioning; T2, specific conditioning; T3, pre-competition; T4, competition). Pearsons and Student’s tests were used to evaluate the association with seasonal best (SB) time, maximal strength (flat bench, deadlift, squat), pre- vs. post- repeated-sprint training (4x4 of 80m sprints), and T1 to T4 progression. We also assessed how a specific nutritional plan (diet, n=4; non-diet, n=3 ) impacted performance and body composition. RESULTS: Between T4 and T1, independently of diet, we measured a median reduction of many skinfold (SF) sites, specifically the 7-site SF ( females , - 9.9%, P= 0.08 ; non-dieting males , -3.7%, P= 0.07 ), which was more marked in those athletes who followed the diet (7SF, -28.6%, P= 0.05 ). By combining the BIVA regional values, we developed a sprinter performance index (SPI) able to discriminate between top and low SB female groups (100m, P=0.003; 200m, P=0.04). SPI/h showed direct correlation with SB (r=-0.7, P=0.02 ), following seasonal fluctuations in performance and arm strength. Women SB significantly correlated with several indices of lean body mass, with an important decrease in leg impedance (Z) and leg phase angle (PhA), indicative of premature performance drop (T4-T3). Male sprinters who followed the diet prolonged their peak performance, along with an increase in SPI/h between T4-T3, and improved their SB (100m: -0.29s, P=0.03; 200m: - 0.44s, n.s.). The non-diet group experienced a progressive decline in arm Z and leg reactance (Xc) after T2, and a drop in the leg PhA (T4-T3). Arm Xc was the only discriminant between faster (100m: average 10.75s; 200m: average 21.71s) and slower (100m: average 11.54 s; 200m: average 23.57s) male sprinters (28.7Ω vs. 26.9Ω, P=0.03 ), showing a correlation with SB (r=-0.6). Both females and males exhibited a reduction of parallel reactance (XcP) concomitant to reaching peak performance. For female athletes, the repeated-sprint test revealed a sharp decrease in leg PhA (-3.8%, P=0.04), increase in arm resistance ( R) and arm Xc (8.5% and 10%, respectively), and a significant rise in arm XcP (6.9%). Men only exhibited a certain drop in arm PhA (-2.7%, P=0.07) and arm Xc (-2.4%, P=0.03). CONCLUSION: We formulated important regional BIVA criteria for coaches and nutritionists to plan macrocycles and mesocycles, especially for female athletes. Regional BIVA pinpointed essential physiological changes that would be masked if looking at whole body measurements only. Based on our data, arm Xc may explain most of the variation in performance, supporting the concept that arm fatigue and strength is a key factor in sprinting propulsion.
Read CV Luigi PasiniECSS Paris 2023: CP-AP11
INTRODUCTION: Carbohydrate is an important energy source particularly during supramaximal exercise such as 800-m running event [1]. Blood lactate and glucose concentrations ([BLa] and [BGlu], respectively) have been widely accepted as good indicators of the usage of carbohydrates by muscles. Blood lactate kinetics indicators after high-intensity running reflect closely the lactate metabolic response implemented during exercise [2], and that of variables have been shown to be correlated with 800-m performance [3, 4]. However, these reported data were measured in the laboratory and the exercise duration was shorter than the 800-m event. It has also been shown that [BGlu] increases markedly after strenuous exercise (i.e. exercise-induced hyperglycemia) [5], but the relationship between high-intensity exercise and changes in [BGlu] has not been investigated. The aim of this study was to investigate the relationship between the variables in [BLa] and [BGlu] from the kinetics following 800-m trial and that of performance. METHODS: In this study, 6 male well-trained middle-distance runners performed an 800-m time trial (800-m TT) on the outdoor track. [BLa] and [BGlu] were collected from the fingertip before and after the trial (i.e. the rest and recovery period, respectively). Using a biexponential time function, lactate exchange ability (γ1), lactate removal ability (γ2), and the quantity of lactate accumulated (QLaA), which can be interpreted as the amount of produced lactate during exercise, was calculated from individual blood lactate recovery data [2, 6]. The delta (∆) of [BGlu] was the difference between [BGlu] at rest and peak following the 800-m TT. The data are reported as mean ± standard deviation. Pearson correlation coefficients were used to determine the correlation between the variables (i.e. γ1, γ2, QLaA and Δ[Glu]) and 800-m performance. Statistical significance was set at p < 0.05. RESULTS: The time of 800-m TT was 119.14 ± 4.26 (sec). γ1, γ2, QLaA and Δ[BGlu] were 0.149 ± 0.08 (/min), 0.014 ± 0.08 (/min), 683.5 ± 131.68 (mmol) and 3.1 ± 0.9 (mmol/L), respectively. Whereas No significant correlations were detected between γ1, γ2 and 800-m TT (γ1: r = 0.46, ns; γ2: r = -0.51, ns), there is a significant relationship between QLaA and 800-m TT (r = -0.90, p < 0.05). In addition, Δ[BGlu] was strongly correlated with 800-m TT (r = -0.81; p < 0.05). CONCLUSION: These results suggested that not only [BLa] but also [BGlu] after exercise could evaluate the supramaximal exercise performance, especially QLaA and Δ[BGlu] may be more highly associated with performance than other variables. The ability to mobilize more carbohydrates and produce more lactate may have a positive impact on 800-m running performance.
Read CV Takeru INABAECSS Paris 2023: CP-AP11