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Human Metabolic Heat
Published in Ken Parsons, Human Heat Stress, 2019
There is a linear relationship between heart rate and activity level (hence metabolic rate — ISO 8996, 2004; NIOSH, 2016). That is, from heart rates above resting level, and levels significantly influenced by psychological factors, up to maximum heart rates where maximum oxygen uptake occurs (VO2 max). Heart rate is also related to hormone distribution and thermoregulation but activity level dominates. The actual heart rate of a person is related to individual factors, and in particular, their fitness, often represented by their VO2 max. So there is no direct relationship between the average heart rate of a group and average metabolic rate or one relationship between heart rate and metabolic rate for all people. We, therefore, need to determine this relationship for individuals. The usefulness of this method is then to be able to estimate metabolic rate for an individual, from their heart rate, which is easier to measure in practical contexts than using indirect calorimetry.
Acute L-glutamine supplementation does not improve gastrointestinal permeability, injury or microbial translocation in response to exhaustive high intensity exertional-heat stress
Published in European Journal of Sport Science, 2022
Henry B. Ogden, Joanne L. Fallowfield, Robert B. Child, Glen Davison, Simon C. Fleming, Simon K. Delves, Alison Millyard, Caroline S. Westwood, Joseph D. Layden
Maximal oxygen uptake (V̇O2max) was determined using an incremental treadmill test (Desmo HP, Woodway GmbH, Weil am Rhein, Germany) to volitional exhaustion in normothermic laboratory conditions (18–22°C, 40–60% RH). Following a five-minute warm-up at 6 km·h−1, the test began at a speed of 10 km·h-1 on a 1% inclination. The treadmill speed was then increased at 1 km·h−1 increments every three minutes until reaching 13 km·h−1, when inclination was then increased by 2% every two minutes. The test was terminated when the participant reached volitional exhaustion. The criteria used to establish a true VO2max included three from: (1) a plateau in VO2 (an increase ≤ 2 ml·kg·min−1) despite increasing exercise intensity; (2) a respiratory exchange ratio ≥ 1.15; (3) a heart rate ≤ 10 b·min−1 of the age-predicted maximum (220-age); and (4) a rating of perceived exertion of 20. The highest 30 s average V̇O2 was taken to be V̇O2max.
Does aerobic performance define match running performance among professional soccer players? A position-specific analysis
Published in Research in Sports Medicine, 2021
Toni Modric, Sime Versic, Damir Sekulic
The most important parameters for the evaluation of AP are maximal oxygen uptake (VO2max) and anaerobic threshold (AnT) (Mehmet et al., 2017). VO2max is defined as the highest oxygen uptake that can be achieved during dynamic exercise with large muscle groups (Wagner, 1996). Currently, professional soccer players’ VO2max varies from 55 to 65 ml kg−1 min−1 (Metaxas, 2021; Silva et al., 2011). AnT is defined as the highest exercise intensity, heart rate, or oxygen uptake working dynamically with large muscle groups in which the production and clearance of lactate are approximately the same (Hoff et al., 2002). AnT can be evaluated from blood lactate level changes (i.e., metabolic acidosis) or from non-invasive gas exchange measurements due to the nonlinear increase in carbon dioxide production and ventilation (Beaver et al., 1986; Mehmet et al., 2017; Wasserman et al., 1973). It has been reported that AnT in soccer players occurs at velocities ranging from 13.0 to 15.0 km/h (Silva et al., 2011) and at 55–75% of VO2max (Chmura et al., 2015).
Effects of 8-week endurance and resistance training programmes on cardiovascular stress responses, life stress and coping
Published in Journal of Sports Sciences, 2020
Participants performed the 2-km UKK walk test to indirectly measure aerobic capacity (Oja & Tuxworth, 1995). This test provides an index of aerobic capacity and an estimate of maximal oxygen uptake (VO2max) and has been validated for adults who are free from illnesses that disable walking and from cardiovascular illnesses (Laukkanen et al., 2000; Oja et al., 1991). The walks took place on a 400-m outdoor-track. The instruction for the walks was “Walk the distance as fast as you can, but do not risk your health”. Heart rate was monitored throughout the walks by a wireless chest heart rate transmitter and a wrist monitor recorder (Suunto T6 c, Suunto, Finland). The mean rate during the last 60 s of the walk was considered the walking heart rate. Participants were asked to refrain from fat eating, alcohol drinking and intensive physical activity for at least 1 day prior to the test day.