Publications by authors named "Sebastien Racinais"

Article Synopsis
  • This study explored the impact of heat exposure on muscle and brain oxygen levels during repeated treadmill sprints by using statistical parametric mapping (SPM).
  • Eleven male participants completed sets of sprints in both hot (38 °C) and temperate (25 °C) environments while their muscle and cerebral oxygenation were monitored.
  • Results showed that heat significantly decreased muscle oxygen levels and limited brain blood flow during sprints and early recovery, highlighting the importance of SPM for analyzing oxygenation data.
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Recovery methods, such as thermal interventions, have been developed to promote optimal recovery and maximize long-term training adaptations. However, the beneficial effects of these recovery strategies remain a source of controversy. This narrative review aims to provide a detailed understanding of how cold and heat interventions impact long-term training adaptations.

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Background: Animal research suggests that repeated heat exposures may stimulate skeletal muscle protein synthesis and downregulate protein degradation.

Hypothesis: Repeated heat exposures during ankle immobilization and rehabilitation would preserve human muscle strength and mass.

Study Design: Controlled laboratory study.

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Article Synopsis
  • * Data on injuries were collected from 10 championships, showing a total of 1203 injuries across 29,579 athlete starts; results indicated that higher UTCI correlated with lower rates of time-loss injuries, especially muscle injuries.
  • * Specifically, athletes in sprints, hurdles, and throws experienced a reduced incidence of both overall and time-loss muscle injuries at higher feels-like temperatures.
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Sports medicine physicians and physiotherapists commonly use cryotherapy (eg, ice application) postinjury to decrease tissue temperature with the objective of reducing pain, limiting secondary injury and inflammation, and supporting healing. However, besides the analgesic effect of cryotherapy, a literature search revealed no evidence from human studies that cryotherapy limits secondary injury or has positive effects on tissue regeneration. Thus, our current understanding of the potential mechanisms and applications of cryotherapy largely relies on the results from animal studies.

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This case study aims to examine changes in the lower limb joint kinematic profile and performance stability induced by repeated ski runs in two world-class alpine skiers. Two Olympic medallist alpine skiers were tested during their slalom training, with continuous recording of right knee and hip angles, along with turn time and run time. The eight runs of the training session were analysed with linear mixed models.

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The upcoming Paris 2024 Olympic and Paralympic Games could face environmental challenges related to heat, air quality and water quality. These challenges will pose potential threats to athletes and impact thousands of stakeholders and millions of spectators. Recognising the multifaceted nature of these challenges, a range of strategies will be essential for mitigating adverse effects on participants, stakeholders and spectators alike.

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Several International Federations (IFs) employ specific policies to protect athletes' health from the danger of heat. Most policies rely on the measurement of thermal indices such as the Wet Bulb Globe Temperature (WBGT) to estimate the risk of heat-related illness. This review summarises the policies implemented by the 32 IFs of the 45 sports included in the Paris 2024 Olympic Games.

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Fascicle force-length relationship is one major basic mechanical property of skeletal muscle, subsequently influencing movement mechanics. While force-length properties are increasingly described through ultrafast ultrasound imaging, their test-retest reliability remains unknown. Using ultrafast ultrasound, and electrically evoked contractions at various ankle angles, gastrocnemius medialis fascicle force-length relationship was assessed twice, few days apart, in sixteen participants.

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Background: Repeated exposure to heat (ie, plasma volume expansion) or altitude (ie, increase in total hemoglobin mass), in conjunction with exercise, induces hematological adaptations that enhance endurance performance in each respective environment. Recently, combining heat and altitude training has become increasingly common for athletes preparing to compete in temperate, sea-level conditions.

Purpose: To review the physiological adaptations to training interventions combining thermal and hypoxic stimuli and summarize the implications for temperate, sea-level performance.

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Article Synopsis
  • The study focused on understanding how running in different temperatures (temperate vs hot) affects the dynamics of the gastrocnemius medialis (GM) muscle during exercise.
  • 15 participants completed a running task while their muscle behavior and temperature were monitored using ultrafast ultrasound before, during, and after a 40-minute run.
  • Results showed that despite increased body temperatures and heart rates in hotter conditions, muscle-tendon properties and fascicle behavior remained unchanged regardless of exercise duration or temperature, suggesting heat does not negatively impact muscle performance during prolonged running.
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We characterized the magnitude and range of gait asymmetry during self-paced treadmill running. On an instrumented treadmill, twelve trained runners (11 males, 1 female) completed a 30-min self-paced run, during which participants were instructed to cover the most distance possible. Ground reaction force recordings at a constant velocity corresponding to 70% of their maximal aerobic velocity (13.

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  • - The study aimed to explore how repeated-sprint cycling training in low oxygen (hypoxia) compared to regular oxygen levels (normoxia) impacts sprint performance and force-velocity (F-V) profiles in elite female rugby sevens players.
  • - Eighteen players were split into two groups, undergoing four sessions of cycling sprints in either hypoxia or normoxia, alongside their regular training, with assessments taken before and after the training period.
  • - The results showed no significant changes in 50-meter running sprint performance or F-V measurements, suggesting that the short training duration might not be adequate to produce measurable effects.
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A growing number of companies are developing or using wearable sensor technologies that can monitor, analyse and transmit data from humans in real time that can be used by the sporting, biomedical and media industries. To explore this phenomenon, we describe and review two high-profile sporting events where innovations in wearable technologies were trialled: the Tokyo 2020 Summer Olympic Games (Tokyo 2020, Japan) and the 2022 adidas Road to Records (Germany). These two major sporting events were the first time academic and industry partners came together to implement real-time wearable solutions during major competition, to protect the health of athletes competing in hot and humid environments, as well as to better understand how these metrics can be used moving forwards.

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  • This study examined the effects of three recovery methods (active recovery, hot-water immersion, and cold-water immersion) on elite skaters after an intense training session.
  • The results showed that active recovery and hot-water immersion led to slightly higher power output in subsequent cycling tests compared to cold-water immersion.
  • No significant differences were found in lactate levels or perceived exertion across the recovery methods, and further research is recommended with larger sample sizes for more comprehensive conclusions.
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Purpose: To compare the effects of graded hypoxia during exhaustive intermittent cycling on subsequent rapid and maximal torque-production capacity.

Methods: Fifteen well-trained cyclists repeated intermittent cycling bouts (15 s at 30% of anaerobic power reserve; rest = 45 s) until exhaustion at sea level (FiO2 ∼0.21/end-exercise arterial oxygen saturation ∼96%), moderate hypoxia (FiO2 ∼0.

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Purpose: To investigate the effects of a training camp with heat and/or hypoxia sessions on hematological and thermoregulatory adaptations.

Methods: Fifty-six elite male rugby players completed a 2-week training camp with 5 endurance and 5 repeated-sprint sessions, rugby practice, and resistance training. Players were separated into 4 groups: CAMP trained in temperate conditions at sea level, HEAT performed the endurance sessions in the heat, ALTI slept and performed the repeated sprints at altitude, and H + A was a combination of the heat and altitude groups.

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Non-communicable diseases (NCDs), including coronary heart disease, stroke, hypertension, type 2 diabetes, dementia, depression and cancers, are on the rise worldwide and are often associated with a lack of physical activity (PA). Globally, the levels of PA among individuals are below WHO recommendations. A lack of PA can increase morbidity and mortality, worsen the quality of life and increase the economic burden on individuals and society.

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Purpose: The objective of this study is to investigate the effectiveness of novel repeated-sprint training in hypoxia (RSH) protocol, likely maximizing hypoxic stimulus (higher than commonly used) while preserving training quality (interset rest in normoxia).

Methods: Twenty-three world-class female rugby sevens players performed four repeated-sprint training sessions (4 sets of 5 × 5-s cycle sprints-25-s intersprint recovery and 3-min interset rest) under normobaric hypoxia (RSH, exercise and interset rest at FiO 2 of 10.6% and 20.

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The purpose of this study was to characterize thermoregulatory and performance responses of elite road-race athletes, while competing in hot, humid, night-time conditions during the 2019 IAAF World Athletic Championships. Male and female athletes, competing in the 20 km racewalk ( = 20 males, 24 females), 50 km racewalk ( = 19 males, 8 females), and marathon ( = 15 males, 22 females) participated. Exposed mean skin (T) and continuous core body (T) temperature were recorded with infrared thermography and ingestible telemetry pill, respectively.

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Repeated heat treatment has been shown to induce oxidative adaptations in cell cultures and rodents, but similar work within human models is scarce. This study investigated the effects of 6 weeks of localized heat therapy on near-infrared spectroscopy-(NIRS) derived indices of muscle oxidative and microvascular function. Twelve physically active participants (8 males and 4 females, age: 34.

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Purpose: Heat acclimation (HA) is recommended before competing in hot and humid conditions. HA has also been recently suggested to increase muscle strength, but its effects on human's muscle and tendon mechanical properties are not yet fully understood. This study investigated the effect of active HA on gastrocnemius medialis (GM) muscle-tendon properties.

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