0000000000141449
AUTHOR
Christophe Hausswirth
showing 14 related works from this author
Influence d'une supplémentation en vitamines sur le rendement de la locomotion après une épreuve d'ultratrail
2006
International audience; Aim: The purpose of this study was to study changes in gross efficiency of locomotion after a prolonged trail running race (3000 m up and 300 m down). The second purpose was to investigate the effectiveness of supplementation in vitamin on gross efficiency variability.Materials and methods: Twenty-two well-trained endurance runners took part in this study. They had to perform four sub maximal tests before, 24, 48 and 72 hours after the race in order to estimate gross efficiency of locomotion and a maximal contraction test in the same period. They were divided in two groups either with supplementation (Isoxan Endurance ®) or without (placebo).Results: In both groups w…
Muscle activation during cycling at different cadences: Effect of maximal strength capacity
2007
International audience; The purpose of this study was to examine the influence of maximal strength capacity on muscle activation, during cycling, at three selected cadences: a low cadence (50 rpm), a high cadence (110 rpm) and the freely chosen cadence (FCC). Two groups of trained cyclists were selected on the basis of the different maximal isokinetic voluntary contraction values (MVCi) of their lower extremity muscles as follow: Fmin (lower MVCi group) and Fmax (higher MVCi group). All subjects performed three 4-min cycling exercises at a power output corresponding to 80 % of the ventilatory threshold under the three cadences. Neuromuscular activity of vastus lateralis (VL), rectus femoris…
Vitamin and Mineral Supplementation and Neuromuscular Recovery after a Running Race
2006
International audience; Purpose: This double-blind study investigated the effects of vitamin and mineral complex supplementation on the neuromuscular function of the knee-extensor muscles after a prolonged trail running race. Methods: Twenty-two well-trained endurance runners took either placebo (Pl group) or vitamins and minerals (Vm group) for 21 d before the race and for 2 d after the race. Maximal voluntary contractions (MVC) and surface EMG activity of the vastus lateralis (VL) muscle were recorded before (pre) and 1 h (post), 24 h (post 24) and 48 h (post 48) after the race. Central activation ratio (CAR), neural (M-wave), and contractile (muscular twitch) properties of the quadriceps…
Age-Related Decline in Olympic Triathlon Performance: Effect of Locomotion Mode
2010
This study describes the decline in performance with age during Olympic triathlon Age Groups World Championships among the different locomotion modes. Mean performance of top 10 performers were analyzed for each group of age using the exponential model proposed by Baker, Tang, and Turner (2003, Experimental Aging Research, 29, 47-65). Comparison in performance decline was done between locomotion modes. Decline in performance in triathlon as a function of age follows an exponential model. A significant interaction effect between age and locomotion mode was observed on performance values. In swimming, a significant decrease was observed close to 5% per year after 45 years. Decline in performa…
Neuromuscular fatigue following high versus low-intensity eccentric exercise of biceps brachii muscle
2009
International audience; Purpose: This study investigated neuromuscular fatigue following high versus low-intensity eccentric exercise corresponding to the same amount of work.Methods: Ten volunteers performed two eccentric exercises of the elbow flexors: a high-intensity versus a low-intensity exercise. Maximal voluntary contraction torque and surface electromyography of the biceps brachii muscle were recorded before, immediately and 48 h after exercises. Maximal voluntary activation level, neural (M-wave) and contractile (muscular twitch) properties of the biceps brachii muscle were analysed using electrical stimulation techniques.Results: Maximal voluntary contraction torque was significa…
Evolution of electromyographic signal, running economy, and perceived exertion during different prolonged exercises
2000
International audience; The purpose of this study was to compare the electromyographic (EMG) signal of the vastus lateralis muscle obtained during a run section of a triathlon and at the end of a prolonged run performed at the same running velocity. Seven subjects were studied on three occasions: a 2 h 15 min triathlon (30 min swimming, 60 min cycling, and 45 min treadmill running at 75% of the maximal aerobic speed), a 2 h 15 min run, where the last 45 min (Prolonged Run, PR) were run at the same speed as the Triathlon Run (TR) on a motorized treadmill, and a 45 min Isolated Run (IR) performed at the same TR and PR velocity. The three experimental trials were randomised. Oxygen uptake (VO …
Evidence of neuromuscular fatigue after prolonged cycling exercise
2000
International audience; Purpose: The purpose of this study was to analyze the effects of prolonged cycling exercise on metabolic, neuromuscular, and biomechanical parameters. Methods: Eight well-trained male cyclists or triathletes performed a 2-h cycling exercise at a power output corresponding to 65% of their maximal aerobic power. Maximal concentric (CON; 60, 120, 240°s 1), isometric (ISO; 0°s 1), and eccentric (ECC; 120,-60°s 1) contractions, electromyographic (EMG) activity of vastus lateralis (VL) and vastus medialis (VM) muscles were recorded before and after the exercise. Neural (M-wave) and contractile (isometric muscular twitch) parameters of quadriceps muscle were also analyzed u…
Effect of cycling cadence on subsequent 3 km running performance in well trained triathletes * Commentary
2003
Objectives: To investigate the effect of three cycling cadences on a subsequent 3000 m track running performance in well trained triathletes. Methods: Nine triathletes completed a maximal cycling test, three cycle-run succession sessions (20 minutes of cycling + a 3000 m run) in random order, and one isolated run (3000 m). During the cycling bout of the cycle-run sessions, subjects had to maintain for 20 minutes one of the three cycling cadences corresponding to 60, 80, and 100 rpm. The metabolic intensity during these cycling bouts corresponded approximately to the cycling competition intensity of our subjects during a sprint triathlon (> 80% VO2max). Results: A significant effect of the p…
Effets d'une complémentation nutritionnelle en vitamines et minéraux sur la chute de force et les marqueurs biologiques consécutifs à un exercice exc…
2007
Purpose. – The effects of vitamins and minerals complex supplementation on maximal voluntary contraction decrease (FMV) and biological markers following an eccentric exercise at old people. Method. – Sixteen elderly subjects took either placebo (Pl group) or vitamins and minerals (Isoxan Senior, NHS, Rungis, France) (group S) for 21 d before an eccentric exercise and for 3 d after the exercise. The FMV and surface EMG activity (RMS) of the vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) were recorded before (Pre), immediately after (Post), 24 h (Post 24) and 48 h (Post 48) after the exercise. CCVThe creatine kinase (CK), lactate deshydrogenase, malondialdehyde, and tumor…
Neuromuscular fatigue following constant versus variable-intensity endurance cycling in triathletes
2008
International audience; The aim of this study was to determine whether variable power cycling produced greater neuromuscular fatigue of knee extensor muscles than constant power cycling at the same mean power output. Eight male triathletes (age : 33 ± 5 yr, mass : 74 ± 4 kg, OV&2max : 62 ± 5 ml.kg-1.min-1, maximal aerobic power : 392 ± 17 W) performed two 30 min trials on a cycle ergometer in a random order. Cycling exercise was performed either at a constant power output (CP) corresponding to 75% of the maximal aerobic power (MAP) or a variable power output (VP) with alternating ± 15%, ± 5%, and ± 10% of 75% MAP approximately every 5 min. Maximal voluntary contraction (MVC) torque, maximal…
Effects of a trail running competition on muscular performance and efficiency in well-trained young and master athletes
2010
International audience; To determine the acute effects of a trail running competition and the age-dependent differences between young and master athletes, 23 subjects [10 young (30.5 ± 7 years), 13 master (45.9 ± 5.9 years)] participated in a 55-km trail running competition. The study was conceived as an intervention study compromising pre, post 1, 24, 48 and 72 h measurements. Measurements consisted of blood tests, ergometer cycling and maximal isometric voluntary contractions (MVC). Parameters monitored included MVC, twitch-and M-wave properties, EMG (RMS) of the vastus lateralis, two locomotion efficiency calculations and muscle damage markers in the blood (CK, LDH). Results indicate pos…
Carbohydrate ingestion does not influence the change in energy cost during a 2-h run in well-trained triathletes
1999
The aim of this study was to examine whether the increase in the energy cost of running (C(r)), previously reported to occur at the end of a prolonged run, could be influenced by the ingestion of either an artificially sweetened placebo (Pl) or a 5.5% carbohydrate (CHO) solution. Ten well-trained triathletes completed three testing sessions within a 3-week period. The aim of the first session was to determine maximal oxygen uptake (VO(2)(max)) and the velocity associated with ventilatory threshold (nu(VT)). The second and the third sessions were composed of two submaximal treadmill runs (20 min long, 0% grade, performed at nu(VT)), before and after an 80-min overground run, also conducted a…
Effect of pedalling rates on physiological response during endurance cycling
2001
International audience; This study was undertaken to examine the effect of different pedalling cadences upon various physiological responses during endurance cycling exercise. Eight well-trained triathletes cycled three times for 30 min each at an intensity corresponding to 80% of their maximal aerobic power output. The first test was performed at a freely chosen cadence (FCC); two others at FCC-20% and FCC +20%, which corresponded approximately to the range of cadences habitually used by road racing cyclists. The mean (SD) FCC, FCC-20% and FCC + 20% were equal to 86 (4), 69 (3) and 103 (5) rpm respectively. Heart rate (HR), oxygen uptake (VO2), minute ventilation (VE) and respiratory excha…
Altération des performances neuromusculaires après un exercice physique prolongé. Analyse comparée d'une épreuve de marathon et de triathlon
1998
The aim of this study was to compare the effects of a marathon and a triathlon on isometric and dynamic neuromuscular performances. Seven triathletes took part in 3 experimental situations : a 2 h 15 mn triathlon (TRI) (30 min swimming, 60 min cycling and 45 min running), a 2 h 15 mn marathon (MA) and a 45 min isolated run done at triathlon speed. The results showed a reduction of the isometric endurance time for knee extensor muscles (35 % of maximal voluntary contraction) after TRI (41 ± 24 %) and after MA (59 ± 19 %). The height of rise of the center of gravity of the counter-movement jumps (CMJ) was also significantly lower after MA (-12 ± 1 cm) than after TRI (-2,5 0,5 cm). Kinetic ana…