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Julien Robineau, Mathieu Lacome, Julien Piscione, Xavier Bigard and Nicolas Babault

Purpose:

To assess the impact of 2 high-intensity interval-training (HIT) programs (short interval vs sprint interval training) on muscle strength and aerobic performances in a concurrent training program in amateur rugby sevens players.

Methods:

Thirty-six amateur rugby sevens players were randomly assigned to strength and short interval training (INT), strength and sprint interval training (SIT), or a strength-only training group (CON) during an 8-wk period. Maximal strength and power tests, aerobic measurements (peak oxygen uptake [VO2peak] and maximal aerobic velocity), and a specific repeated-sprint ability (RSA) test were conducted before and immediately after the overall training period.

Results:

From magnitude-based inference and effect size (ES ± 90% confidence limit) analyses, the current study revealed substantial gains in maximal strength and jump-height performance in all groups. The difference in change of slow concentric torque production was greater in CON than in SIT (0.65 ± 0.72, moderate). VO2peak and, consequently, mean performance in the RSA test were improved in the SIT group only (0.64 ± 0.29, moderate; –0.54 ± 0.35, moderate).

Conclusions:

The study did not emphasize interference on strength development after INT but showed a slight impairment of slow concentric torque production gains after SIT. Compared with INT, SIT would appear to be more effective to develop VO2peak and RSA but could induce lower muscle-strength gains, especially at low velocity.

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Andre-Xavier Bigard, Pierre-Yves Guillemot, Jean-Yves Chauve, François Duforez, Pierre Portero and Charles-Yannick Guezennec

The purpose of the present study was to determine the nutritional intake of 11 skippers during the four stages of a solitary long-distance offshore race. Body weight significantly decreased during the race (−1.31 ±0.32 kg, range 3.5 to 0.1 kg, p < .01). Total daily energy intake was 18.53 ± 0.71 MJ ⋅ day-1 during the race, and it correlated negatively with the race duration of each leg. Energy intake during the race was ~ 19% greater than that determined for a subgroup of 5 sailors during a control period 2 months after the race. Nutrient intake expressed as percentage calories of total energy was estimated at 50%, 35%, and 15% for carbohydrate, fat, and protein, respectively. Voluntary fluid intake decreased with increasing race duration (p < .001). Despite high energy intakes, sailors lost body weight during the solitary offshore race. It was not possible to conclude that this change in body weight was related to fluid loss and/or a discrepancy between energy intake and energy expenditure.

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Marina Fabre, Christophe Hausswirth, Eve Tiollier, Odeline Molle, Julien Louis, Alexandre Durguerian, Nathalie Neveux and Xavier Bigard

While effects of the two classes of proteins found in milk (i.e., soluble proteins, including whey, and casein) on muscle protein synthesis have been well investigated after a single bout of resistance exercise (RE), the combined effects of these two proteins on the muscle responses to resistance training (RT) have not yet been investigated. Therefore, the aim of this study was to examine the effects of protein supplementation varying by the ratio between milk soluble proteins (fast-digested protein) and casein (slow-digested protein) on the muscle to a 9-week RT program. In a double-blind protocol, 31 resistance-trained men, were assigned to 3 groups receiving a drink containing 20g of protein comprising either 100% of fast protein (FP(100), n = 10), 50% of fast and 50% of slow proteins (FP(50), n = 11) or 20% of fast protein and 80% of casein (FP(20), n = 10) at the end of training bouts. Body composition (DXA), and maximal strength in dynamic and isometric were analyzed before and after RT. Moreover, blood plasma aminoacidemia kinetic after RE was measured. The results showed a higher leucine bioavailability after ingestion of FP(100) and FP(50) drinks, when compared with FP(20) (p< .05). However, the RT-induced changes in lean body mass (p < .01), dynamic (p < .01), and isometric muscle strength (p < .05) increased similarly in all experimental groups. To conclude, compared with the FP(20) group, the higher rise in plasma amino acids following the ingestion of FP(100) and FP(50) did not lead to higher muscle long-term adaptations.