AGE-RELATED CHANGES IN NEUROMUSCULAR FUNCTION AND PERFORMANCE FOLLOWING A HIGH-INTENSITY INTERMITTENT TASK IN ENDURANCE TRAINED MEN

International audienceBackground: A greater attention has been focused on the need to design strategies to increase functional capacities in older populations. This has raised several questions regarding the ability of regular endurance training to preserve functional capacity with age.Objective: The purpose of this study was to examine the age-associated changes in neuromuscular function in endurance trained men before and after a high-intensity, intermittent fatigue task.Method: 26 healthy endurance trained male subjects: 16 old (59-79 yrs) and 10 young (20-34 yrs) men per-formed a high-intensity, intermittent fatigue exercise corresponding to 10 sets of 10 repetitions on a hori-zontal leg press at 70% of the individual one repetition maximum. Maximal voluntary contractions (MVC) and evoked contractions of the knee extensors muscles were performed before and after the exercise.Results: Decreases in MVC (old: -9.7 % and young: -14.3 %) and electromyographic activity were not different between groups. Peak twitch torque was reduced only for the old men and no changes in voluntary activa-tion and M-wave properties were recorded in either group.Conclusion: The present study indicates in endurance trained men aged 59-79 years that muscle functional capacities are maintained despite losses in strength and contractile function related to the age

Variability in energy cost of running at the end of a triathlon and a marathon

International audienceThe aim of this study was to investigate the increase in energy cost of running occurring at the end of a triathlon and a marathon event and to link them to the metabolic and hormonal changes, as well as to variations in stride length. Seven subjects took part in 3 experimental situations: a 2 h 15 min triathlon (30 min swimming, 60 min cycling and 45 min running), a 2 h 15 min marathon (MR) were the fast 45 min were run at the same speed as the triathlon run (TR), and a 45 min isolated run (IR) done at triathlon speed. The results show that energy cost during MR was higher than during TR (p < 0.01) (+ 8.9 %). Similar observations were made for pulmonary ventilation (+ 7.9 %) and heart rate (+ 6.3 %). Moreover, the values were significantly greater than the values obtained during the IR. TR and MR lead to greater weight loss (p < 0.01) (2.4±0.3 kg) than IR (1 ± 0.2 kg). The triathlon and the marathon produced a large decrease in plasma volume (respectively 19.6 ± 1.4 % and 12.9 ± 1.1 %) compared to IR (2 ± 0.4 %). Plasma renin activity was higher for the triathlon and the marathon than for the IR (p < 0.01). MR produces a significantly greater increase in plasma free fatty acids (F.F.A.) than TR (p < 0.05) and IR (p < 0.01). In addition, the F.F.A. at the end of TR were significantly higher than IR (p < 0.05). At the end of the trial the mean stride lengths for TR and IR were greater (+ 15 %) (p <0.01) than for MR. This study, carried out with subjects running overground, confirms the decrease in running efficiency previously shown at the end of a laboratory triathlon, and demonstrates that this decrease is lower than that occurring during a marathon

Whole-body cryotherapy does not augment adaptations to high-intensity interval training

The aim of this study was to investigate the effects of regular post-exercise whole-body cryotherapy (WBC) on physiological and performance adaptations to high-intensity interval training (HIT). In a two-group parallel design, twenty-two well-trained males performed four weeks of cycling HIT, with each session immediately followed by 3 min of WBC (−110 °C) or a passive control (CON). To assess the effects of WBC on the adaptive response to HIT, participants performed the following cycling tests before and after the training period; a graded exercise test (GXT), a time-to-exhaustion test (Tmax), a 20-km time trial (20TT), and a 120-min submaximal test (SM120). Blood samples were taken before and after training to measure changes in basal adrenal hormones (adrenaline, noradrenaline, and cortisol). Sleep patterns were also assessed during training via wrist actigraphy. As compared with CON, the administration of WBC after each training session during four weeks of HIT had no effect on peak oxygen uptake (V˙ role= presentation \u3eV˙O2peak) and peak aerobic power (Ppeak) achieved during the GXT, Tmax duration and work performed (WTmax), 20TT performance, substrate oxidation during the SM120, basal adrenaline/noradrenaline/cortisol concentrations, or sleep patterns (P \u3e 0.05). These findings suggest that regular post-exercise WBC is not an effective strategy to augment training-induced aerobic adaptations to four weeks of HIT

Relationships between triathlon performance and pacing strategy during the run in an international competition

PURPOSE: The purpose of the present study was to examine relationships between athlete\u27s pacing strategies and running performance during an international triathlon competition. METHODS: Running split times for each of the 107 finishers of the 2009 European Triathlon Championships (42 females and 65 males) were determined with the use of a digital synchronized video analysis system. Five cameras were placed at various positions of the running circuit (4 laps of 2.42 km). Running speed and an index of running speed variability (IRSVrace) were subsequently calculated over each section or running split. RESULTS: Mean running speed over the first 1272 m of lap 1 was 0.76 km·h-1 (+4.4%) and 1.00 km·h-1 (+5.6%) faster than the mean running speed over the same section during the three last laps, for females and males, respectively (P \u3c .001). A significant inverse correlation was observed between RSrace and IRSVrace for all triathletes (females r = -0.41, P = .009; males r = -0.65, P = .002; and whole population -0.76, P = .001). Females demonstrated higher IRSVrace compared with men (6.1 ± 0.5 km·h-1 and 4.0 ± 1.4 km·h-1, for females and males, respectively, P = .001) due to greater decrease in running speed over uphill sections. CONCLUSIONS: Pacing during the run appears to play a key role in high-level triathlon performance. Elite triathletes should reduce their initial running speed during international competitions, even if high levels of motivation and direct opponents lead them to adopt an aggressive strategy

The Cosmed K4 telemetry system as an accurate device for oxygen uptake measurements during exercise

International audienceThe purpose of this study was to test the accuracy of oxygen uptake (VO2) measurements using the Cosmed K4 portable telemetry system. This system of higher technology than the original Cosmed K2 device, contains a CO2 electrode allowing measurements alternatively by either the Cosmed K4 system (K4) or the CPX Medical Graphics (CPX) during a maximum oxygen uptake (VO 2 max) ergocycle test, at rest and during several submaximal exercices (25, 50 and 75% of maximal work rate) in seven subjects. Heart rate values were comparable for exercise at the same work stage during gas collection using the two systems, indicating that the physiological stresses were similar. The VO 2 values did not significantly differ at rest (4.40 ± 0.83 vs 4.16 ± 0.58 ml • min-1 kg-1), at 25% Wmax (20.97 ± 1.31 vs 21.32 ± 2.54 ml • min-1 • kg-1), at 50% Wmax (33.32 ± 3.92 vs 33.50 ± 3.51 ml • min-1. kg-1), at 75% Wmax (47.01 ± 7.51 vs 47.49 ± 7.11 ml • min-1. kg-') and at maximal intensities (62.07 ± 8.48 vs 62.84 ± 11.31 ml • min-1. kg-1) using K4 and CPX devices, respectively. The results of this study indicated that the K4 system was accurate for all oxygen uptake measurements from rest to maximum exercise levels

Effects of Whole-Body Cryotherapy vs. Far-Infrared vs. Passive Modalities on Recovery from Exercise-Induced Muscle Damage in Highly-Trained Runners

Enhanced recovery following physical activity and exercise-induced muscle damage (EIMD) has become a priority for athletes. Consequently, a number of post-exercise recovery strategies are used, often without scientific evidence of their benefits. Within this framework, the purpose of this study was to test the efficacy of whole body cryotherapy (WBC), far infrared (FIR) or passive (PAS) modalities in hastening muscular recovery within the 48 hours after a simulated trail running race. In 3 non-adjoining weeks, 9 well-trained runners performed 3 repetitions of a simulated trail run on a motorized treadmill, designed to induce muscle damage. Immediately (post), post 24 h, and post 48 h after exercise, all participants tested three different recovery modalities (WBC, FIR, PAS) in a random order over the three separate weeks. Markers of muscle damage (maximal isometric muscle strength, plasma creatine kinase [CK] activity and perceived sensations [i.e. pain, tiredness, well-being]) were recorded before, immediately after (post), post 1 h, post 24 h, and post 48 h after exercise. In all testing sessions, the simulated 48 min trail run induced a similar, significant amount of muscle damage. Maximal muscle strength and perceived sensations were recovered after the first WBC session (post 1 h), while recovery took 24 h with FIR, and was not attained through the PAS recovery modality. No differences in plasma CK activity were recorded between conditions. Three WBC sessions performed within the 48 hours after a damaging running exercise accelerate recovery from EIMD to a greater extent than FIR or PAS modalities

Periodization of carbohydrate intake: Short-term effect on performance

“Sleep-low” consists of a sequential periodization of carbohydrate (CHO) availability—low glycogen recovery after “train high” glycogen-depleting interval training, followed by an overnight-fast and light intensity training (“train low”) the following day. This strategy leads to an upregulation of several exercise-responsive signaling proteins, but the chronic effect on performance has received less attention. We investigated the effects of short-term exposure to this strategy on endurance performance. Methods: Following training familiarization, 11 trained cyclists were divided into two groups for a one-week intervention—one group implemented three cycles of periodized CHO intake to achieve the sleep-low strategy over six training sessions (SL, CHO intake: 6 g·kg-1·day-1), whereas the control group consumed an even distribution of CHO over the day (CON). Tests were a 2 h submaximal ride and a 20 km time trial. Results: SL improved their performance (mean: +3.2%; p < 0.05) compared to CON. The improvement was associated with a change in pacing strategy with higher power output during the second part of the test. No change in substrate utilization was observed after the training period for either group. Conclusion: Implementing the “sleep-low” strategy for one week improved performance by the same magnitude previously seen in a three-week intervention, without any significant changes in selected markers of metabolism. © 2016 by the authors; licensee MDPI, Basel, Switzerland.Background

Prospects for the upskilling of general workers in Britain : a case study comparison of the English and Irish dairy processing industries

While there is strong evidence that longstanding systemic weaknesses in the British economy continue to lead to negative strategic, skills and employment outcomes across much of British industry, there has in recent years been a notable lack of empirical research in the skills and employment relations fields aimed at examining the potential for upskilling or 'employment upgrading' to be achieved for general workers. It is apparent that issues of political economy and in particular the relationship between institutional contexts, competitive performance and skills/employment outcomes at sector level have been largely neglected. This thesis seeks to partly fill this gap by presenting data from a comparative case study of the English and Irish dairy processing industries, the central focus of which was an examination of the consequences for company strategies, employee skills, employment and wage levels of the overriding emphasis on the promotion of competition and efficiency and the lack of a strong industrial policy in the former, and in contrast the existence of a strategic and resource intensive industrial policy in the latter. This research provides an ideal opportunity to address two issues of current theoretical concern, namely the potential for an industrial policy to facilitate upskilling and debates regarding the advantages and disadvantages of different 'varieties of capitalism'. In general terms, the industrial policy context in England was found to inhibit investment in product development and in particular moves by processors in to higher value, advanced market niches, with negative consequences for employee skills and comparatively low wages resulting. However these outcomes were to some extent mitigated by the presence in the UK industry of a number of high-investing foreign multinationals who undertook very substantial new product development, thereby facilitating some notable upskilling for production workers. In Ireland, while significant limitations in both the nature and extent of impact were identified, the 'benign' industrial policy context was found to support processors in moving into advanced product markets, and consequently underpinned the creation of substantial opportunities for upskilling alongside a high standard of living for production operatives. However skills outcomes at workplace level were found to be heavily contingent on a number of different factors, with upskilling not found to be either an automatic or likely consequence of a move up market. In addition, the fact that vocational training in the industry continued to be of a predominantly informal, on-the-job nature was found to create significant tensions and lead to dissatisfaction on the part of production operatives. This research demonstrates the general value of the adoption of a supportive/strategic industrial policy in terms of the potentially positive consequences resulting for strategy, skills and employment outcomes. However it also highlights how the potential of such a policy to facilitate upskilling is limited, being heavily influenced/determined by the structural makeup and key characteristics and trends within particular sectors and product markets. In addition, the need to address broader systemic issues relating to work organisation, the labour process and the nature of vocational training systems is emphasised. More broadly, the findings highlight the problematic nature of the central theoretical conclusion and policy recommendation from the varieties of capitalism literature, that liberal market economies like the UK should accentuate the deregulated/fluid nature of capital, labour and product markets and focus attention on activities/sectors dominated by 'radical' as opposed to 'incremental' innovation; and in contrast arguably demonstrate the need for and potential of the development of thick institutional structures and substantial industry support measures, even in 'traditional' sectors such as dairy.EThOS - Electronic Theses Online ServiceEconomic and Social Research Council (Great Britain) (ESRC) (R42200034459)Warwick Business SchoolUniversity College, Dublin. Faculty of CommerceUniversity College, Dublin. Dept. of Industrial RelationsGBUnited Kingdo

Effets d'une alcalose induite sur les paramètres métaboliques et sanguins lors d'un test: Cyclisme et Course à pied chez des triathlètes entraînés

International audienc

Endurance and strength training effects on physiological and muscular parameters during prolonged cycling

International audiencePurpose: This study investigated the effects of a combined endurance and strength training on the physiological and neuromuscular parameters during a 2-hour cycling test.Methods: Fourteen triathletes were assigned to an endurance-strength training group (ES) and an endurance-only training group (E). They performed 3 experimental trials before and after training: an incremental cycling test to exhaustion, a maximal concentric lower-limbs strength measurement and a 2-hour cycling exercise. Physiological parameters, free cycling chosen cadence (FCC) and the EMG of Vastus Lateralis (VL) and Rectus Femoris (RF) were analysed during the 2-hour cycling task.Results: The results showed that the maximum strength and the isometric maximal voluntary contraction (isoMVC) after training were significantly higher (P<0.01) and lower (P<0.01) than before training, respectively in ES and E groups. The physiological variables measured during the cycling tests and the progressive increase (P<0.01) in EMGi (VL) and EMGi (RF) throughout the 2-hour cycling test did not differ between the two groups before and after training, except for the variation of EMGi (VL) over the cycle time which was stabilized during the second hour of the 2-hour cycling test due to training in ES group. The decrease in FCC observed in pre-training (P<0.01) was also replaced by a steady FCC for the ES-group during the second hour of exercise.Conclusion: This study confirmed the decrease in the FCC with exercise duration and demonstrated that a specific combined endurance and strength training can prevent this decrease during a 2-hour constant cycling exercise