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

Effects of high vs moderate-intensity training on neuroplasticity and functional recovery after focal ischemia

Background and Purpose: This study was designed to compare the effects of high-intensity interval training (HIT) and moderate-intensity continuous training (MOD) on functional recovery and cerebral plasticity during the first 2 weeks following cerebral ischemia. Methods: Rats were randomized as follows: Control (n=15), SHAM (n=9), MCAO (n=13), MCAO-D1 (n=7), MOD (n=13) and HIT (n=13). Incremental tests were performed at day 1 (D1) and 14 (D14) to identify the running speed associated with the lactate threshold (SLT) and the maximal speed (Smax). Functional tests were performed at D1, D7 and D14. Microglia form, cytokines, p75NTR, KCC2 and NKCC1 expression were made at D15. Results-HIT was more effective to improve the endurance performance than MOD and induced a fast recovery of the impaired forelimb grip force. The Iba-1 positive cells with amoeboid form and the pro- and anti-inflammatory cytokine expression were lower in HIT group, mainly in the ipsilesional hemisphere. A p75NTR overexpression is observed on the ipsilesional side together with a restored NKCC1/KCC2 ratio on the contralesional side. Conclusions-Low-volume HIT based on lactate threshold appears to be more effective after cerebral ischemia than work-matched MOD to improve aerobic fitness, grip strength and might promote cerebral plasticity

Factors influencing pacing in triathlon

Triathlon is a multisport event consisting of sequential swim, cycle, and run disciplines performed over a variety of distances. This complex and unique sport requires athletes to appropriately distribute their speed or energy expenditure (ie, pacing) within each discipline as well as over the entire event. As with most physical activity, the regulation of pacing in triathlon may be influenced by a multitude of intrinsic and extrinsic factors. The majority of current research focuses mainly on the Olympic distance, whilst much less literature is available on other triathlon distances such as the sprint, half-Ironman, and Ironman distances. Furthermore, little is understood regarding the specific physiological, environmental, and interdisciplinary effects on pacing. Therefore, this article discusses the pacing strategies observed in triathlon across different distances, and elucidates the possible factors influencing pacing within the three specific disciplines of a triathlon

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

Influence of race distance and biological sex on age-related declines in triathlon performance. Part A

This study examined the effect of biological sex and race distance on the age-related declines in swimming, cycling, running and overall performances of the sprint, Olympic, Half-Ironman and Ironman triathlons. Individual discipline and overall performance time of the top 20% non-elite males (n=468) and females (n=146) were compared by categorizing into four 10-year age-groups (20-29, 30-39, 40-49, 50+ years) and normalising to the mean performance time of the fastest age-group for each race. An earlier, larger and faster rate of decline (p=0.01) in performance with ageing was observed in females (≥30 years, 9.3%, 3.0% per decade respectively) and males (≥40 years, 5.9%, 2.2% per decade, respectively) for the longer events (half-Ironman and Ironman) compared with the shorter distances (sprint and Olympic, ≥50 years for both sexes). A greater magnitude of decline was observed in swimming for both sexes, especially in the longer events, when compared with cycling and running (12.8%, 5.6%, 9.3% for females, 9.4%, 3.7%, 7.3% for males, in the swim, cycle and run disciplines, respectively). These results indicate that both race distance and biological sex influence the age-related decline in triathlon performance and could aid athletes in optimising training programs to attenuate the age-related declines in performance across different disciplines and distances. Specifically, older athletes may benefit from greater emphasis on swim training and factors that may influence performance during longer distance triathlons

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

Influence of age and sex on pacing during sprint, Olympic, half-Ironman and Ironman triathlons. Part B

The aim of this study was to investigate the influence of biological sex and age on the pacing strategies adopted by non-drafting top triathletes during the cycle and run disciplines of a Sprint, Olympic, half-Ironman and Ironman triathlon. Split times of the top 20% non-elite males (n=468) and females (n=146) were determined using official race transponders and a video capture system for pre-determined sections of the cycle and run disciplines of four triathlon distances. Indices of pacing were calculated to compare between sexes and age-groups. Results of this study indicated that different pacing strategies were adopted between athletes of different age and sex over the various triathlon disciplines and distances. Females were more aggressive during the initial stages of the cycling discipline across all distances (sprint - 2.1% p=0.024; Olympic - 1.6%, p=0.011; half-Ironman- 1.5%, p\u3c0.001; Ironman - 1.7%, p\u3c0.001 higher relative to mean) compare with males. Younger athletes (20-29 y) tend to begin the run faster (2.0 to 3.0% faster than other age-groups, p\u3c0.029) during the sprint, Olympic and half-Ironman triathlons. These results indicate that different pacing strategies are adopted by non-drafting top athletes of different age and sex. Optimal pacing strategies may differ between sex and ages; therefore individuals may need to trial different strategies to develop their own optimal pacing profile for triathlon events of varying distances

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

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