The microvasculature is important for both health and exercise tolerance in a range of populations. However, methodological limitations have meant changes in microvascular blood flow are rarely ...assessed in humans during interventions designed to affect skeletal muscle blood flow such as the wearing of compression garments. The aim of this study is, for the first time, to use contrast‐enhanced ultrasound to directly measure the effects of compression on muscle microvascular blood flow alongside measures of femoral artery blood flow and muscle oxygenation following intense exercise in healthy adults. It was hypothesized that both muscle microvascular and femoral artery blood flows would be augmented with compression garments as compared with a control condition. Ten recreationally active participants completed two repeated‐sprint exercise sessions, with and without lower‐limb compression tights. Muscle microvascular blood flow, femoral arterial blood flow (2D and Doppler ultrasound), muscle oxygenation (near‐infrared spectroscopy), cycling performance, and venous blood samples were measured/taken throughout exercise and the 1‐hour post‐exercise recovery period. Compared with control, compression reduced muscle microvascular blood volume and attenuated the exercise‐induced increase in microvascular velocity and flow immediately after exercise and 1 hour post‐exercise. Compression increased femoral artery diameter and augmented the exercise‐induced increase in femoral arterial blood flow during exercise. Markers of blood oxygen extraction in muscle were increased with compression during and after exercise. Compression had no effect on blood lactate, glucose, or exercise performance. We provide new evidence that lower‐limb compression attenuates the exercise‐induced increase in skeletal muscle microvascular blood flow following exercise, despite a divergent increase in femoral artery blood flow. Decreased muscle microvascular perfusion is offset by increased muscle oxygen extraction, a potential mechanism allowing for the maintenance of exercise performance.
The purpose of this study was to compare the
combined effects of creatine monohydrate (Cr) and beta-alanine (BA) with their
isolated use on performance and physiological parameters during repeated ...sprint
sequences (RSS). Forty-four male (n=34) and female (n=10) amateur team- and
racket sport players (25.1±3.1 years; 175.2±9.8 cm; 76.0±10.3 kg; 15.2±6.8%
body fat) performed ten repetitions of 6-s sprints with departure every 30 s,
before and after a 28-day supplementation period with either Cr (n=11, 5 g‧day-1),
BA (n=10, 6 g‧day-1), combined Cr and BA (n=12, 5 g‧day-1
of Cr plus 6g‧day-1 of BA) or placebo (11 g‧day-1 of rice
flour). Peak (PP) and mean power (MP), performance decrement (%Dec), heart rate
(HR), blood lactate concentration (LA) and perceived exertion (RPE) were
measured. Analyses of variance (ANOVA) were used to determine the effects of
groups (Cr, BA, CrBA, P), sprint number (1 to 10), and time (pre- vs.
post-supplementation) on all variables. A significant increase in PP was shown in
the post- compared to the pre-supplementation in Cr (+5.2%) and BA (+5.2%)
groups only (p<.05), and significant decreases in MP in all groups (3.7% to
6.4%, p<.05), except BA. %Dec was significantly decreased post-supplementation
in the Cr group only (17.4%, p<.05). No effects were shown on HR, RPE and LA
(p<.05). These results show no additional benefits of the combination of Cr
and BA on RSS performance and suggest that longer sprint or total exercise
duration might be necessary to observe the benefits of the combined
supplementation.
Kyles, A, Oliver, JL, Cahill, MJ, Lloyd, RS, and Pedley, J. Linear and change of direction repeated sprint ability tests: a systematic review. J Strength Cond Res 37(8): 1703-1717, 2023-The ability ...to repeatedly sprint is important in many sports, but there is no established protocol for measuring repeated sprint ability (RSA). The purpose of this review was to identify overground RSA protocols previously reported in the literature and to recommend standardized protocols. A systematic review of the literature was used to identify studies that have used an RSA test, with data describing protocol design extracted. One hundred eight studies were included in the review, across which 47 unique protocols were identified. Eighteen protocols included at least one change of direction (COD), and this increased mean sprint time compared with linear RSA tests (7.26 ± 1.84 vs. 4.48 ± 1.02 seconds). There was considerable variability across protocols regarding sprint distance (20-40 m), sprint repetitions (3-15), recovery duration (10-60 seconds), recovery type (active vs. passive), and work-to-rest ratio (≤1:1.4-19.2). Separate protocols are needed for linear and COD tests, and these should reflect the brief nature of intense periods of competition and stress the ability to recover. Based on data across studies for protocol design and to ensure a demanding work-to-rest ratio, it is suggested that a linear RSA should comprise 6 × 30 m sprints separated by 15 seconds of active recovery. To provide some parity to linear tests, to keep work duration brief and to maintain a demanding work-to-rest ratio, a COD RSA should comprise 6 × 30 m shuttle sprints (15 + 15 m), providing one change of direction (180° COD), and maintaining a 15-second active recovery.
The aim of this study was to assess elite women's basketball game performance. Five elite women's games (3 Italian first division and 2 Euroleague) were analyzed for individual and team time-motion ...analyses. The individual analysis evaluated the players' movement patterns with particular focus on high-intensity activity (HIA), sprint activity, and repeated sprint events (RSEs). Team analysis included live time (LT), stoppage time (ST), and their ratio, transfer (TR) phases, and half court and full court actions. The frequency of occurrence of changes of activities was n = 576 ± 110, one every 2.56 seconds of LT. Total HIA was 8.5 ± 1.8% of LT and no significant differences between quarter periods were observed. In general, players performed linear sprints (48.3 ± 2.9%) over 1-5 m distance (56.8 ± 5.6%). The occurrence of RSE was 4.4 ± 1.7, with 58.6 ± 18.5% passive recovery between sprints. Team analysis showed no significant difference between games for LT and ST phases (ratio = 1.18 ± 0.25). For game analysis, LT and ST were 43.4 ± 7.8% and 51.1 ± 8.4%, respectively. A difference between games was found for half court actions (p < 0.01) and TR phases (p ≤ 0.05). Moreover, 1 TR and 2 TR were the most performed (45.3 and 23.9%) actions. These results encourage coaches to include repeated sprint ability with mainly linear and short sprints into a comprehensive training program.
To examine the degree of neuromuscular fatigue development along with changes in muscle metabolism during two work-matched high-intensity intermittent exercise protocols in trained individuals.
In a ...randomized, counter-balanced, crossover design, 11 endurance-trained men performed high-intensity intermittent cycle exercise protocols matched for total work and including either multiple short-duration (18 × 5 s; SS) or long-duration (6 × 20 s; LS) sprints. Neuromuscular fatigue was determined by preexercise to postexercise changes in maximal voluntary contraction force, voluntary activation level and contractile properties of the quadriceps muscle. Metabolites and pH were measured in vastus lateralis muscle biopsies taken before and after the first and last sprint of each exercise protocol.
Peak power output (11% ± 2% vs 16% ± 8%, P < 0.01), maximal voluntary contraction (10% ± 5% vs 25% ± 6%, P < 0.05), and peak twitch force (34% ± 5% vs 67% ± 5%, P < 0.01) declined to a lesser extent in SS than LS, whereas voluntary activation level decreased similarly in SS and LS (10% ± 2% vs 11% ± 4%). Muscle phosphocreatine before the last sprint was 1.5-fold lower in SS than LS (P < 0.001). Preexercise to postexercise intramuscular accumulation of lactate and H was twofold and threefold lower, respectively, in SS than LS (P < 0.001), whereas muscle glycogen depletion was similar in SS and LS. Rate of muscle glycolysis was similar in SS and LS during the first sprint, but twofold higher in SS than LS during the last sprint (P < 0.05).
These findings indicate that, in endurance-trained individuals, multiple long-sprints induce larger impairments in performance along with greater degrees of peripheral fatigue compared to work-matched multiple short-sprints, with these differences being possibly attributed to more extensive intramuscular accumulation of lactate/H and to lower rates of glycolysis during multiple long-sprint exercise.
The purpose of this longitudinal study was to clarify the motion characteristics of children who had greatly improved their sprint speed in the middle grades of elementary school over a one-year ...period. The sprint motions of 23 children (12 boys and 11 girls) in the third and fourth grades were filmed and compared by classifying them into 2 groups: a superior group, who improved their running speed relatively significantly, and an inferior group, who increased their running speed only slightly. The motions of children who had improved their sprinting speed significantly in one year were characterized by an increase in the swing-back angular velocity of the hip joint, the degree of knee joint extension during ground contact, and the angular velocity of the extension. In addition, the whole leg swing speed and the ankle joint angle at ground contact were found to be smaller. Except for the swing-back angular velocity of the hip joint, these motions differed from the rational motions clarified in previous biomechanics research. The findings of this study indicate that some middle-grade elementary school children improve their sprinting speed significantly over the course of a year, even if it is transformed into a motion that is at odds with the rational motion, or the motion to be aimed for, described in previous studies.
Thompson, K, Whinton, AK, Ferth, S, Spriet, LL, and Burr, JF. Moderate load resisted sprints do not improve subsequent sprint performance in varsity-level sprinters. J Strength Cond Res 35(1): 72-77, ...2021-Resisted sprint training (RST) is commonly used for performance enhancement in athletics and team sports to develop acceleration ability. Evidence suggests that RST may be effective as a short-term intervention to improve successive sprints. Although these improvements have been measured in team sport athletes, limited research has considered the acute effects of RST training in sprint-trained athletes. Therefore, the aim of the current study was to determine whether performing RST with varsity-level sprinters using sled-equivalent resistive loads of ∼45% body mass results in a potentiation effect, leading to improvements in subsequent maximal sprint performance over 0-5 m and 0-20 m. Competitive sprinters (n = 20) were randomly assigned to perform a pre/post maximal 20-m sprint separated by either 3 resisted (RST group) or unresisted (URS group) sprints. The RST or URS protocol was performed on 4 occasions separated by at least 7 days. No significant differences were observed between the RST and URS groups comparing changes in sprint times over 0-5 m (URS Δ <0.01 ± 0.03 seconds, RST Δ <0.01 ± 0.03 seconds) and 0-20 m (URS Δ 0.013 ± 0.04 seconds, RST Δ <0.01 ± 0.04 seconds). We conclude that resisted sprints using sled-equivalent loads of 45% body mass are ineffective at inducing a potentiating effect on subsequent sprint performance in varsity-level sprinters. In this population of trained athletes, greater loads may be necessary to induce a potentiating effect.
Kristiansen, M, Sydow Krogh Pedersen, A-M, Sandvej, G, Jørgensen, P, Jakobsen, JV, de Zee, M, Hansen, EA, and Klitgaard, KK. Enhanced maximal upper-body strength increases performance in sprint ...kayaking. J Strength Cond Res 37(4): e305-e312, 2023-The association between upper-body strength and performance in 200-m flat-water sprint kayak is not fully elucidated. Therefore, the aim of study 1 was to investigate the relationship between upper-body strength and kayaking performance. In study 2, the aim was to perform a randomized training intervention to investigate whether a causal relationship was present between an increase in strength and an actual change in 200-m kayaking performance. In study 1, 37 (22 men and 15 women) elite kayak paddlers performed tests of maximal power output, isometric force, 1 repetition maximum (1RM), and 40 seconds of maximal repetition number in bench press and bench pull and a 30-second all-out on-water sprint kayak test. In study 2, 26 (16 men and 10 women) national elite junior A, U23, and senior kayak paddlers were allocated into 2 groups: a training group (TRAIN) and a maintenance group (MAIN). Each group completed a 6-week strength training intervention with the purpose of either increasing 1RM in bench press (TRAIN) or maintaining strength (MAIN). Pre- and posttests were performed in 200-m kayak ergometer sprint, 1RM bench press, and 1RM bench pull. In study 1, 1RM in bench press was the best predictor of 30-second on-water kayaking performance with a regression coefficient of 0.474. In study 2, TRAIN significantly increased 1RM strength in bench press (pre: 87.3 ± 21.2 kg, post: 93.9 ± 21.3 kg, p = 0.001) and bench pull (pre: 84.2 ± 15.3 kg, post: 86.0 ± 15.1 kg, p = 0.025). In the 200-m kayak ergometer sprint test, TRAIN significantly decreased the time to complete the test (pre: 44.8 ± 4.3 seconds, post: 44.3 ± 4.3 seconds, p = 0.042). In bench press, 1RM was the best predictor of 200-m kayaking, and an increase in bench press 1RM resulted in increased kayaking performance.
The main aim of this study was to compare bone health parameters in young active sprinters and young active men.
Twenty-six young sprinters and 26 young men participated in this study. Weight and ...height were measured, and body mass index (BMI) was calculated. Body composition, whole body (WB) BMC, lumbar spine (L1–L4) BMD, total hip (TH) BMD and forearm BMD were evaluated by DXA. Physical performance variables, daily calcium intake, daily protein intake and physical activity level were assessed. Age, height, lean mass, WB BMC and forearm BMD were not significantly different between the two groups. L1–L4 BMD, TH BMD, vertical jump and maximal strength of the lower limbs were higher in sprinters compared to active men.
The current study suggests that sprinters have higher lumbar spine and hip BMD values compared to active men. The current study has several implications in the field of prevention of osteoporosis in men.
Le but de cette étude était de comparer des marqueurs de santé osseuse chez des jeunes hommes pratiquant le sprint et des jeunes hommes actifs.
Vingt-six jeunes sprinteurs et 26 hommes actifs ont participé à cette étude. La composition corporelle, le contenu minéral osseux (CMO) du corps entier, la densité minérale osseuse (DMO) du rachis lombaire (L1–L4), la DMO de la hanche totale et la DMO de l’avant-bras ont été évaluées par DXA. Les paramètres de performance physique, la consommation calcique journalière, la consommation protéique journalière et le niveau d’activité physique ont été évaluées. L’âge, la taille, la masse maigre, le CMO du corps entier et la DMO de l’avant-bras n’étaient pas significativement différents entre les deux groupes. La DMO du rachis lombaire, la DMO de la hanche, la détente verticale et la force maximale des membres inférieurs étaient supérieures chez les jeunes sprinteurs par rapport aux hommes actifs.
La présente étude suggère que la DMO du rachis lombaire et la DMO de la hanche sont plus élevées chez les sprinteurs par rapport aux hommes actifs. Ces résultats ont des applications pratiques dans le domaine de la prévention de l’ostéoporose masculine.
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