Effect of Cold on Proprioception and Cognitive Function in Elite Alpine Skiers

Purpose: To determine the effect of cold ambient conditions on proprioception and cognitive function in elite alpine skiers. Methods: 22 high-level alpine skiers and 14 control participants performed a proprioceptive-acuity (active movement-extent discrimination) and a cognitive (planning task) test in cold (8°C) and temperate (24°C) ambient conditions. Results: All participants displayed an increase in thermal discomfort and the amount of negative affects in the cold environment (all P < .05). Average proprioceptive acuity was significantly better in the elite skiers (0.46° ± 0.12°) than in the control group (0.55° ± 0.12°) (P < .05) and was not affected by cold ambient conditions, except for a shift in the pattern of error (over- vs underestimation, P < .05). Cognitive performance was similar between elite skiers and control participants in temperate environments but decreased in the cold in the control group only (P < .05) becoming lower than in elite skiers (P < .05). Conclusion: Elite alpine skiers showed a significantly better proprioceptive acuity than a control population and were able to maintain their performance during a cognitive task in a cold environment. Accepted author manuscript version reprinted, by permission, from International Journal of Sports Physiology and Performance, 2017, 12(1), p69-74, http://dx.doi.org/10.1123/ijspp.2016-0002. © Human Kinetics, Inc

Psycho-physiological responses to perceptually-regulated interval runs in hypoxia and normoxia

We investigated whether perceptually-regulated high-intensity intervals in hypoxia are associated with slower running velocities versus normoxia, when physiological responses and exercise-related sensations remain the same. Nineteen trained runners (33.4 ± 9.1 years) completed a high-intensity interval running protocol (4 × 4-min intervals at a clamped perceived rating exertion of 16 on the 6-20 Borg scale, 3-min passive recoveries) in either hypoxic (HYP; FiO2 15.0%) or normoxic (NOR; FiO2 20.9%) conditions. Participants adjusted to a progressively slower running velocity from interval 1-4 (-7.0%), and more so in HYP vs. NOR for intervals 2, 3 and 4 (-4.6%, -6.4% and - 7.9%, respectively; p < .01). Heart rate increased from interval 1-4 (+4.8%; p < .01), independent of condition. Arterial oxygen saturation was lower in HYP vs. NOR (86.0% vs. 94.8%; p < .01). Oxyhemoglobin (-23.7%) and total hemoglobin (-77.0%) decreased, whilst deoxyhemoglobin increased (+44.9%) from interval 1-4 (p < .01), independent of condition. Perceived recovery (-41.6%) and motivation (-21.8%) were progressively lower from interval 1-4, and more so in HYP vs. NOR for intervals 2, 3 and 4 (recovery: -8.8%, -24.2% and - 29.3%; motivation: -5.3%, -20.3% and - 22.4%, respectively; p < .01). Perceived breathlessness (+18.6%), limb discomfort (+44.0%) and pleasure (-32.2%) changed from interval 1-4, with significant differences (+21.8%, +11.3% and - 31.3%, respectively) between HYP and NOR (p < .01). Slower interval running velocities in hypoxia achieve similar heart rate and muscle oxygenation responses to those observed in normoxia when perceptually-regulated, yet at the expense of less favourable exercise-related sensations

Acute Psychophysiological Responses to Cyclic Variation of Intermittent Hypoxic Exposure in Adults with Obesity

Hobbins, Liam, Olivier Girard, Nadia Gaoua, and Steve Hunter. Acute psychophysiological responses to cyclic variation of intermittent hypoxic exposure in adults with obesity. High Alt Med Biol 00:000-000, 2019. Background: We compared acute psychophysiological responses with a single intermittent hypoxic exposure (IHE)/normoxic exposure trial with varying cycle lengths in adults with obesity. Materials and Methods: Eight obese adults (body mass index = 33.0 ± 2.2 kg/m2) completed three 60-minute IHE trials (passive seating), separated by 7 days. Trials comprised 30-minute hypoxia/30-minute normoxia (inspired oxygen fraction = 12.0%/20.9%) over Short (15 × 2/2 minutes), Medium (10 × 3/3 minutes), and Long (5 × 6/6 minutes) hypoxic/normoxic cycles and a control trial (60-minute normoxia). Results: Arterial oxygen saturation was lower during hypoxic periods of Long versus Medium and Short trials (90.1% vs. 93.0% and 94.2%; p = 0.02 and p = 0.05), with no differences between Short and Medium. Prefrontal cortex oxygenation was lower (-5.1%) during all IHE interventions versus control (p < 0.02), independent of cycle length. Perceived breathlessness was unaffected during IHE but increased 15 minutes after exposure versus baseline (+34%; p = 0.04). Breathlessness was lowest after Short versus control from 15 to 60 minutes (-7%; p = 0.01). Conclusions: When implementing IHE, greater desaturation is observed during longer compared with shorter hypoxic/normoxic cycles in adults with obesity. However, IHE tends to be better tolerated perceptually with shorter rather than longer cycles. Final publication is available from Mary Ann Liebert, Inc., publishers http://dx.doi.org/10.1089/ham.2019.000

Perception, action and cognition of football referees in extreme temperatures: Impact on decision performance

Different professional domains require high levels of physical performance alongside fast and accurate decision-making. Construction workers, police officers, firefighters, elite sports men and women, the military and emergency medical professionals are often exposed to hostile environments with limited options for behavioural coping strategies. In this (mini) review we use football refereeing as an example to discuss the combined effect of intense physical activity and extreme temperatures on decision-making and suggest an explicative model. In professional football competitions can be played in temperatures ranging from -5oC in Norway to 30oC in Spain for example. Despite these conditions, the referee’s responsibility is to consistently apply the laws fairly and uniformly, and to ensure the rules are followed without waning or adversely influencing the competitiveness of the play. However, strenuous exercise in extreme environments imposes increased physiological and psychological stress that can affect decision-making. Therefore, the physical exertion required to follow the game and the thermal strain from the extreme temperatures may hinder the ability of referees to make fast and accurate decisions. Here we review literature on the physical and cognitive requirements of football refereeing and how extreme temperatures may affect referees’ decisions. Research suggests that both hot and cold environments have a negative impact on decision-making but data specific to decision-making is still lacking. A theoretical model of decision-making under the constraint of intense physical activity and thermal stress is suggested. Future naturalistic studies are needed to validate this model and provide clear recommendations for mitigating strategies

Heat acclimation has a protective effect on the central but not peripheral nervous system

This study aimed to clarify the pathway mediating hyperthermia-induced alterations in neural drive transmission, and determine if heat acclimation protects voluntary muscle activation and cognitive function in hyperthermic humans. Electrically evoked potentials (H-reflex and M-wave), executive function (special planning and working memory) and maximal voluntary isometric contractions (120 s) were assessed in fourteen participants in control condition (CON, 24ºC, 40% RH) and hyperthermic states (HYP, 44-50ºC, 50% RH), on consecutive days in a counterbalanced order. Thereafter, Participants were passively heat acclimated for 11 days (1 h per day, 48-50ºC, 50% RH) before repeating the initial assessments. Heat acclimation decreased rectal temperature in CON (-0.2ºC, p0.05), heat acclimation restored executive function, whilst protecting the ability to sustain voluntary activation and torque production during a prolonged contraction in hyperthermia (p<0.05). Ultimately, heat acclimation induces beneficial central but not peripheral neural adaptations

Normobaric hypoxic conditioning to maximise weight-loss and ameliorate cardio-metabolic health in obese populations: A systematic review.

Normobaric hypoxic conditioning (HC) denotes exposure to hypoxia at rest (passive) or combined with exercise (active). HC has been applied acutely (single exposure) and chronically (repeated exposure) to obese populations for managing/increasing cardio-metabolic health and weight loss. Cardio-metabolic health and weight loss responses of obese populations in response to passive and active HC are unclear. A systematic search for articles published between 2000-2017 was carried out. Studies investigating the effects of HC for improving cardio-metabolic health and weight loss of obese populations were included. Studies investigated passive (n = 7; 5 animal, 2 humans), active (n = 4; all humans) and a combination of (n = 4; 3 animal, 1 human) HC to an inspired oxygen fraction between 4.8-15.0%, during a single session and daily sessions per week, lasting between 5 days and 8 months. Passive HC could reduce insulin concentrations (-37-22%) and increase energy expenditure (+12-16). Active HC may reduce body weight (-4-2%) and blood pressure (-8-3%). Inconclusive findings exist in determining the impact of acute and chronic HC on markers of triglycerides, cholesterol levels and fitness capacity. Studies that included animal models involved exposure to severe levels of hypoxia (inspired oxygen fraction of 5.0%; simulated altitude >10,000 m) that are not suitable for human populations. HC demonstrated positive findings in relation to insulin and energy expenditure, and body weight and blood pressure, for improving the cardio-metabolic health and body weight management of obese populations. Responses of plasma biomarkers to passive and active HC in humans is warranted

Running mechanics adjustments to perceptually-regulated interval runs in hypoxia and normoxia

Objectives We determined whether perceptually-regulated, high-intensity intermittent runs in hypoxia and normoxia induce similar running mechanics adjustments within and between intervals. Design Within-participants repeated measures. Methods Nineteen trained runners completed a high-intensity intermittent running protocol (4×4-min intervals at a perceived rating exertion of 16 on the 6–20 Borg scale, 3-min passive recoveries) in either hypoxic (FiO2 =0.15) or normoxic (FiO2 =0.21) conditions. Running mechanics were collected over 10 consecutive steps, at constant velocity (∼15.0±2.0km.h−1), at the beginning and the end of each 4-min interval. Repeated measure ANOVA were used to assess within intervals (onset vs. end of each interval), between intervals (interval 1, 2, 3 vs. 4) and FiO2 (0.15 vs. 0.21) main effects and any potential interaction. Results Participants progressively reduced running velocity from interval 1–4, and more so in hypoxia compared to normoxia for intervals 2, 3 and 4 (P 0.298) and FiO2 (across all intervals P >0.082) main effects or any significant between intervals×within intervals×FiO2 interactions (all P >0.098) for any running mechanics variables. Irrespective of interval number or FiO2, peak loading rate (+10.6±7.7%; P <0.001) and duration of push-off phase (+2.0±3.1%; P =0.001) increased from the onset to the end of 4-min intervals, whereas peak push-off force decreased (−4.0±4.0%; P <0.001). Conclusions When carrying out perceptually-regulated interval treadmill runs, runners adjust to progressively slower velocities in hypoxia compared to normoxia. However, only subtle constant-velocity modifications of their mechanical behaviour occurred within each set, independently of FiO2 or interval number

Development and validation of a scale to measure social isolation in adolescents

Background: There is a lack of questionnaires specifically designed to assess social isolation in adolescents. We developed and validated a self-report measure of social isolation in adolescents, the Social Isolation Questionnaire (QIS). Methods: A literature review on social isolation and mental health in adolescents indicated 20 questions to form QIS. Two cross-sectional surveys with 48 and 1,135 adolescents, respectively, evaluated the reproducibility and validity of QIS. Results: The Bland-Altman plot did not indicate a systematic difference between measurements 15 days apart. Bartlett’s sphericity test verified a correlation between the questions and the Kaiser-Meyer-Olkin test showed good adequacy (0.896) to the factor analysis. Exploratory factor analysis suggested the exclusion of three questions (loading factors <0.3), and eigenvalues (4.9 to 0.8) indicated that the questionnaire should be composed of three factors (dimensions). The Cronbach’s alpha indicated high internal consistency of the 17 questions (0.850 overall; Dimensions: 0.815 ‘feeling of loneliness’; 0.760 ‘friendship’; and, 0.680 ‘Family support’). The QIS score ranged from 0 to 131 (maximum social isolation score). Correlation between QIS and depressive symptoms (r=0.543) indicated the construct validity of QIS. Limitations: We evaluated QIS in the Portuguese version, thus translation and cultural adaptation are necessary to evaluate the questionnaire in other settings. Conclusions: We constructed and validated the QIS questionnaire, a self-administered questionnaire to assess social isolation in adolescents, composed of three dimensions; feeling of loneliness, friendship and family support. The QIS questionnaire seems a very promising tool to support practitioners and researchers in assessing social isolation among adolescents

Training Regimes and Recovery Monitoring Practices of Elite British Swimmers

Consistent prescriptions for event-specific training of swimmers are lacking, which points to likely differences in training practices and a potential gap between practice and scientific knowledge. This study aimed to analyze the distance-specific training load of elite swimmers, derive a consistent training sessions’ description and reflect on the current recommendations for training and recovery. The individual training regimes of 18 elite British swimmers were documented by surveying four swim and two strength and conditioning (S&C) coaches. The annual and weekly training load and content were compared between swimmers competing in sprint, middle and long-distance events. Thematic analysis of the surveys was conducted to identify key codes and general dimensions and to define a unified classification of the swimming and S&C training sessions. Weekly training loads and content of the swim (ƞ2 - effect size; p = 0.016, ƞ2 = 0.423) and S&C (p = 0.028, ƞ2 = 0.38) sessions significantly differed between the groups. Long-distance swimmers swam significantly longer distances (mean ± SD; 58.1 ± 10.2 km vs. 43.2 ± 5.3 km; p = 0.018) weekly but completed similar number of S&C sessions compared to sprinters. The annual swimming load distribution of middledistance specialists did not differ from that of long-distance swimmers but consisted of more S&C sessions per week (4.7 ± 0.5 vs. 2.3 ± 2.3; p = 0.04). Sprinters and middle-distance swimmers swam similar distances per week and completed similar number of S&C sessions but with different proportional content. Whereas all coaches reported monitoring fatigue, only 51% indicated implementing individualized recovery protocols. We propose a consistent terminology for the description of training sessions in elite swimming to facilitate good practice exchanges. While the training prescription of elite British swimmers conforms to the scientific training principles, recommendations for recovery protocols to reduce the risk of injury and overtraining are warranted