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John Seifert, Joseph Harmon and Patty DeClercq

The purpose of this study was to compare fluid retention of carbohydrate plus protein, a carbohydrate-only, and water following 2.5% body weight (BW) loss. Thirteen subjects dehydrated to 2.5% of BW, then ingested a CHO (6%) plus protein drink (1.5%; CP), a 6% CHO drink, or water (WA) at a volume equal to BW loss during a 3-h recovery. Fluid retention was significantly greater for CP (88 ± 4.7%) than CHO (75 ± 14.6%), which was greater than WA (53 ± 16.1%). Serum and urine osmolalities were greater for CP (284.7 ± 5.0; 569.4 ± 291.4 mOsm/kg) than CHO (282.6 ± 5.2; 472.9 ± 291.5 mOsm/kg) which were greater than WA (280.6 ± 5.9, 303.7 ± 251.5 mOsm/kg). Results indicate that fluid retention for CP was 15% greater than CHO and 40% greater than WA. Water ingestion led to a dilution of the serum and resulted in only 53% fluid retention.

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John G. Seifert, Ronald W. Kipp, Markus Amann and Oladele Gazal

This study examined energy and fluid supplementation on indices of muscle damage during alpine skiing. Skiers were assigned to a carbohydrate-protein (CP), placebo (PL), or no fluid (NF) group. CP and PL ingested 1.62 L during and after skiing. Myoglobin did not change from pre-skiing (PS) to 2 h post-skiing (2PS) for CP (24.8 ± 1.4 and 25.6 ± 1.6 ng/mL), but rose significantly from 26.4 ± 1.3 to 40.0 ± 2.8 ng/mL for PL and from 29.0 ± 1.3 to 82.9 ± 3.6 ng/mL for NF. Creatine kinase was maintained from PRE to 2 PS for CP, but increased significantly from 117 ± 7.2 to 174 ± 43.4 U/L for PL and from 126 ± 23.2 to 243 ± 34.3 U/L for NF. This study demonstrates that ingestion of a CP beverage minimized muscle damage indices during skiing compared to PL and NF and that ingesting fluids may also minimize muscle damage compared to a NF condition.

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John Komar, Ross H. Sanders, Didier Chollet and Ludovic Seifert

This study compared interlimb coordination and indicators of swim efficiency and effectiveness between expert and recreational breaststroke swimmers. Arm-leg coordination of 8 expert and 10 recreational swimmers at two different paces, slow and sprint, were compared using relative phase between elbow and knee. For each participant, knee and elbow angles were assessed using a 3-dimensional video analysis system with four below and two above cameras. During each phase of the cycle, indicators of swim efficiency (intracyclic velocity variations) and effectiveness (horizontal distance, velocity peaks, acceleration peaks) were calculated. Two coordination patterns emerged between expert and recreational swimmers, with significant differences in the relative phase at the beginning of a cycle (−172.4° for experts and −106.6° for recreational swimmers) and the maximum value of relative phase (9.1° for experts and 45.9° for recreational swimmers; all P < .05). Experts’ coordination was associated with higher swim effectiveness (higher acceleration peak: 2.4 m/s2 for experts and 1.6 m/s2 for recreational swimmers) and higher distance covered by the center of mass during each phase of the cycle (all P < .05). This study emphasized how experts coordinate arms and legs to achieve effective behavior, therefore exhibiting flexibility, mainly in the timing of the glide phase, to adapt to different speed.

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John G. Seifert, Greg L. Paul, Dennis E. Eddy and Robert Murray

The effects of preexercise hyperinsulinemia on exercising plasma glucose, plasma insulin, and metabolic responses were assessed during 50 min cycling at 62% VO2max. Subjects were fed a 6% sucrose/glucose solution (LCHO) or a 20% maltodextrin/glucose solution (HCHO) to induce changes in plasma insulin. During exercise, subjects assessed perceived nauseousness and lightheadedness. By the start of exercise, plasma glucose and plasma insulin had increased. In the LCHO trial, plasma glucose values significantly decreased below the baseline value at 30 min of exercise. However, by 40 min, exercise plasma glucose and insulin values were similar to the baseline value. Exercise plasma glucose and insulin did not differ from baseline values in the HCHO trial. Ingestion of LCHO or HCHO was not associated with nausea or lightheadedness. It was concluded that the hyperinsulinemia induced by preexercise feediigs of CHO did not result in frank hypoglycemia or adversely affect sensory or physiological responses during 50 min of moderate-intensity cycling.

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Brice Guignard, Annie Rouard, Didier Chollet, Marco Bonifazi, Dario Dalla Vedova, John Hart and Ludovic Seifert

Swimming is a challenging locomotion, involving the coordination of upper and lower limbs to propel the body forward in a highly resistive aquatic environment. During front crawl, freestyle stroke, alternating rotational motion of the upper limbs above and below the waterline, is coordinated with alternating lower limb pendulum actions. The aim of this study was to investigate the upper to lower limbs coordination dynamics of eight male elite front crawlers while increasing swimming speed and disturbing the aquatic environment (i.e., pool vs. flume). Upper to lower limb frequency ratios, coordination, coupling strength, and asymmetry were computed from data collected by inertial measurement units. Significant speed effect was observed, leading to transitions from 1∶1 to 1∶3 frequency ratios (1∶3 overrepresented), whereas 1∶2 frequency ratio was rarely used. Flume swimming led to a significant lower coupling strength at low speeds and higher asymmetries, especially at the highest speeds, probably related to the flume dynamic environment.