Independent, additive and interactive effects of acute normobaric hypoxia and cold on submaximal and maximal endurance exercise.

PURPOSE: To evaluate the independent and combined effects of hypoxia (FiO2 = 13.5%) and cold (- 20 °C) on physiological and perceptual responses to endurance exercise. METHODS: 14 trained male subjects ( V . O2max: 64 ± 5 mL/kg/min) randomly performed a discontinuous maximal incremental test to exhaustion on a motorized treadmill under four environmental conditions: Normothermic-Normoxia (N), Normothermic-Hypoxia (H), Cold-Normoxia (C) and Cold-Hypoxia (CH). Performance and physiological and perceptual responses throughout exercise were evaluated. RESULTS: Maximal WorkLoad (WL) and WL at lactate threshold (LT) were reduced in C (- 2.3% and - 3.5%) and H (- 18.0% and - 21.7%) compared to N, with no interactive (p = 0.25 and 0.81) but additive effect in CH (- 21.5% and - 24.6%). Similarly, HRmax and Vemax were reduced in C (- 3.2% and - 14.6%) and H (- 5.0% and - 7%), showing additive effects in CH (- 7.7% and - 16.6%). At LT, additive effect of C (- 2.8%) and H (- 3.8%) on HR reduction in CH (- 5.7%) was maintained, whereas an interactive effect (p = 0.007) of the two stressors combined was noted on Ve (C: - 3.1%, H: + 5.5%, CH: - 10.9%). [La] curve shifted on the left in CH, displaying an interaction effect between the 2 stressors on this parameter. Finally, RPE at LT was exclusively reduced by hypoxia (p < 0.001), whereas TSmax is synergistically reduced by cold and hypoxia (interaction p = 0.047). CONCLUSION: If compared to single stress exposure, exercise performance and physiological and perceptual variables undergo additive or synergistic effects when cold and hypoxia are combined. These results provide new insight into human physiological responses to extreme environments.

Changes in upper and lower body muscle involvement at increasing double poling velocities: an ecological study.

This study evaluated muscle activity changes in different body compartments during on-snow double poling at increasing velocities. 21 well-trained, male cross-country skiers performed five 3-min double poling trials on a snowy track at 15, 16.5, 18, 19.5, and 21 km/h (set by an audio-pace system). A sixth trial was performed by maintaining a constant maximal speed. Actual skiing velocities were verified using a photocell system. Only 11 subjects met the pre-defined inclusion criteria during the trials and were included in the data analysis. Electromyographical signals from seven muscles, wrist acceleration and heart rate during the last minute of each trial were recorded. Cycle and poling times were measured from acceleration signals; mean muscular activation over a cycle was calculated for each muscle. With increasing double poling velocities from aerobic to maximal intensity (from 65% to 100% of maximal heart rate), upper limb muscles activation was maintained constant (P > 0.05), while trunk and lower limb involvement increased significantly (P < 0.01) with a linear trend. Rectus abdominis and rectus femoris muscles showed the higher rate of change. Trunk and lower limbs provide a progressively greater contribution to the propulsion when increasing double poling velocities are performed, to support the limited capacity of exercise response of upper body muscles. The remarkable rate of involvement of the muscles near the core region of the body becomes strategic to cope with the increased demands of propulsive power.

Injury and Illness Rates During Ultratrail Running.

This study aimed to describe injury/illness rates in ultratrail runners competing in a 65-km race to build a foundation for injury prevention and help race organizers to plan medical provision for these events. Prospectively transcribed medical records were analysed for 77 athletes at the end of the race. Number of injuries/illnesses per 1 000 runners and per 1 000-h run, overall injury/illness rate and 90% confidence intervals and rates for major and minor illnesses, musculoskeletal injuries, and skin disorders were analysed. A total of 132 injuries/illnesses were encountered during the race. The overall injuries/illnesses were 1.9 per runner and 13.1 per 1 000-h run. Medical illnesses were the most prominent medical diagnoses encountered (50.3%), followed by musculoskeletal injuries (32.8%), and skin-related disorders (16.9%). Despite the ultra-long nature of the race, the majority of injuries/illnesses were minor in nature. Medical staff and runners should prepare to treat all types of injuries and illnesses, especially the fatigue arising throughout the course of an ultratrail run and injuries to the lower limbs. Future studies should attempt to systematically identify injury locations and mechanisms in order to better direct injury prevention strategies and plan more accurate medical care.

Acute Exercise Increases Sex Differences in Amateur Athletes' Risk Taking.

The research presented here investigates the interaction between acute exercise, biological sex and risk-taking behavior. The study involved 20 amateur athletes (19-33 years old), 10 males and 10 females, who were asked to undergo subsequent experimental sessions designed to compare their risky behaviors on the Balloon Analogue Risk Task (BART) 34 at rest and while exercising at moderate intensity (60% of their maximal aerobic power). Results showed that physical exercise affected male and female participants differently: Whereas males became more risk seeking, females became more risk averse during exercise.

Effects of a similar amount of regular non-structured or competitive physical activity across late adulthood: a cross-sectional study.

Introduction: Master athletes are examples of successful aging. It is not clear whether it is the competitive-oriented training or just the amount of total regular exercise that reduces the age-related decline in physiological functions. We aimed to compare health-related parameters in competitive (C) and physically active older adults (A) that performed the same weekly physical activity (PA) amount. Methods: Seventeen C and 17 A were matched for age (8 and 9 male participants under and over 70 years old respectively, for both groups) and weekly PA amount (GPAQ). Body composition, leg and arm maximal strength, balance and reaction time were measured; moreover, leg and arm exercise efficiency, estimated VO2max, and VO2/HR relationships were evaluated. Perception of life and sleep quality was also assessed through specific questionnaires (SF-36 and PSQI). The effect of group (C vs. A), age (U70 vs. O70) and their interaction was examined through a Two-Way ANOVA test. Results: C dedicated more time to vigorous PA compared to A (p = 0.03), while less to moderate daily work (p < 0.01) and active commuting (p = 0.06). C exhibited better body composition (all p < 0.05), higher leg maximal strength (p < 0.05) and a trend for elevated arm strength (p = 0.06). Reaction time, leg and arm cycling efficiency were similar in the two groups (all p > 0.05), while balance reduced in A O70. Estimated VO2max was higher for C in leg cycling (p = 0.05) and remained constant across ages (all p > 0.05). VO2/HR relationship, life and sleep quality did not differ for groups and ages. Conclusions: Regular physical exercise of about 6,000 METs/week seems to have a beneficial effect on health-related parameters, both in non-structured and competitive PA, when compared to sedentary behaviour. However, the older adults engaged in competitive training exhibit further advantages: better body composition, higher arm and leg muscle strength, and higher leg VO2max. This study highlights the importance of encouraging active lifestyles for maintaining long-term health, high levels of life quality perception and reducing age-related decline. However, vigorous training suitability needs to be verified by a team of PA specialists.