scholarly journals Application of A Physiological Strain Index in Evaluating Responses to Exercise Stress – A Comparison Between Endurance and High Intensity Intermittent Trained Athletes

2016 ◽  
Vol 50 (1) ◽  
pp. 103-114 ◽  
Author(s):  
Ilona Pokora ◽  
Aleksandra Żebrowska
Keyword(s):  
Heart Rate ◽  
High Intensity ◽  
Morphological Characteristics ◽  
Exercise Stress ◽  
Control Group ◽  
Physiological Strain ◽  
Strain Index ◽  
Physiological Strain Index ◽  
C 50 ◽  
Response To Exercise

AbstractThe study evaluated differences in response to exercise stress between endurance and high-intensity intermittent trained athletes in a thermoneutral environment using a physiological strain index (PSI). Thirty-two subjects participated in a running exercise under normal (23°C, 50% RH) conditions. The group included nine endurance trained athletes (middle-distance runners - MD), twelve high-intensity intermittent trained athletes (soccer players - HIIT) and eleven students who constituted a control group. The exercise started at a speed of 4 km·h–1 which was increased every 3 min by 2 km·h–1 to volitional exhaustion. The heart rate was recorded with a heart rate monitor and aural canal temperature was measured using an aural canal temperature probe. The physiological strain index (PSI) and the contribution of the circulatory and thermal components to the overall physiological strain were calculated from the heart rate and aural canal temperature. The physiological strain index differed between the study and control participants, but not between the MD and HIIT groups. The physiological strain in response to exercise stress in a thermoneutral environment was mainly determined based on the circulatory strain (MD group - 73%, HIIT group – 70%). The contribution of the circulatory and thermal components to the physiological strain did not differ significantly between the trained groups (MD and HIIT) despite important differences in morphological characteristics and training-induced systemic cardiovascular and thermoregulatory adaptations.

scholarly journals Effects of human head hair on performance and thermoregulatory responses during 10-km outdoor running in healthy men

2016 ◽  
Vol 18 (2) ◽  
pp. 155
Author(s):  
Angelo Ruediger Pisani Martini ◽  
João Batista Ferreira-Júnior ◽  
Daniel Barbosa Coelho ◽  
Diego Alcântara Borba ◽  
Leonardo Gomes Martins Coelho ◽  
...  
Keyword(s):  
Heart Rate ◽  
Rectal Temperature ◽  
Heat Storage ◽  
Human Head ◽  
Physiological Strain ◽  
Strain Index ◽  
Healthy Men ◽  
Thermoregulatory Responses ◽  
Head Hair ◽  
Physiological Strain Index

DOI: http://dx.doi.org/10.5007/1980-0037.2016v18n2p155 The aim of the present study was to evaluate the effects of human head hair on performance and thermoregulatory responses during 10-km outdoor running in healthy men. Twelve healthy males (29.5 ± 3.7 years, 174.9 ± 4.3 cm, 72.7 ± 3.2 kg and VO2max 44.6 ± 3.4 ml.kg-1.min-1) participated in two self-paced outdoor 10-km running trials separated by 7 days: 1) HAIR, subjects ran with their natural head hair; 2) NOHAIR, subjects ran after their hair had been totally shaved. Average running velocity was calculated from each 2-km running time. Rectal temperature, heart rate and physiological strain index were measured before and after the 10-km runs and at the end of each 2 km. The rate of heat storage was measured every 2 km. The environmental stress (WBGT) was measured every 10 min. The running velocity (10.9 ± 1 and 10.9 ± 1.1 km.h-1), heart rate (183 ± 10 and 180 ± 12 bpm), rectal temperature (38.82 ± 0.29 and 38.81 ± 0.49oC), physiological strain index (9 ± 1 and 9 ± 1), or heat storage rate (71.9 ± 64.1 and 80.7 ± 56.7 W.m-1) did not differ between the HAIR and NOHAIR conditions, respectively (p>0.05). There was no difference in WBGT between the HAIR and NOHAIR conditions (24.0 ± 1.4 and 23.2 ± 1.5ºC, respectively; p=0.10). The results suggest that shaved head hair does not alter running velocity or thermoregulatory responses during 10-km running under the sun.

Can gender differences during exercise-heat stress be assessed by the physiological strain index?

1999 ◽  
Vol 276 (6) ◽  
pp. R1798-R1804 ◽  
Author(s):  
Daniel S. Moran ◽  
Yair Shapiro ◽  
Arie Laor ◽  
Sharona Izraeli ◽  
Kent B. Pandolf
Keyword(s):  
Gender Differences ◽  
Heat Stress ◽  
Sweat Rate ◽  
Physiological Strain ◽  
Strain Index ◽  
Wide Acceptance ◽  
Physiological Strain Index ◽  
Lower Strain ◽  
And Gender ◽  
C 50

A physiological strain index (PSI) based on rectal temperature (Tre) and heart rate (HR) was recently suggested to evaluate exercise-heat stress. The purpose of this study was to evaluate PSI for gender differences under various combinations of exercise intensity and climate. Two groups of eight men each were formed according to maximal rate of O2 consumption (V˙o 2 max). The first group of men (M) was matched to a group of nine women (W) with similar ( P > 0.001)V˙o 2 max (46.1 ± 2.0 and 43.6 ± 2.9 ml ⋅ kg−1 ⋅ min−1, respectively). The second group of men (MF) was significantly ( P < 0.001) more fit than M or W with V˙o 2 max of 59.1 ± 1.8 ml ⋅ kg−1 ⋅ min−1. Subjects completed a matrix of nine experimental combinations consisting of three different exercise intensities for 60 min [low, moderate, and high (300, 500, and 650 W, respectively)] each at three climates {comfortable, hot wet, and hot dry [20°C 50% relative humidity (RH), 35°C 70% RH, and 40°C 35% RH, respectively]}. No significant differences ( P > 0.05) were found between matched genders (M and W) at the same exposure for sweat rate, relativeV˙o 2 max(%V˙o 2 max), and PSI. However, MF had significantly ( P < 0.05) lower strain than M and W as reflected by %V˙o 2 max and PSI. In summary, PSI applicability was extended for exercise-heat stress and gender. This index continues to show potential for wide acceptance and application.

scholarly journals A physiological strain index to evaluate heat stress

1998 ◽  
Vol 275 (1) ◽  
pp. R129-R134 ◽  
Author(s):  
Daniel S. Moran ◽  
Avraham Shitzer ◽  
Kent B. Pandolf
Keyword(s):  
Heart Rate ◽  
Heat Stress ◽  
Protective Clothing ◽  
Age Groups ◽  
Weight Functions ◽  
Physiological Strain ◽  
Strain Index ◽  
Simultaneous Measurements ◽  
Physiological Strain Index ◽  
Universal Scale

A physiological strain index (PSI), based on rectal temperature (Tre) and heart rate (HR), capable of indicating heat strain online and analyzing existing databases, has been developed. The index rates the physiological strain on a universal scale of 0–10. It was assumed that the maximal Tre and HR rise during exposure to exercise heat stress from normothermia to hyperthermia was 3°C (36.5–39.5°C) and 120 beats/min (60–180 beats/min), respectively. Tre and HR were assigned the same weight functions as follows: PSI = 5(Tre t − Tre0) ⋅ (39.5 − Tre0)−1+ 5(HR t − HR0) ⋅ (180 − HR0)−1, where Tre t and HR t are simultaneous measurements taken at any time during the exposure and Tre0 and HR0 are the initial measurements. PSI was applied to data obtained from 100 men performing exercise in the heat (40°C, 40% relative humidity; 1.34 m/s at a 2% grade) for 120 min. A separate database representing seven men wearing protective clothing and exercising in hot-dry and hot-wet environmental conditions was applied to test the validity of the present index. PSI differentiated significantly ( P < 0.05) between the two climates. This index has the potential to be widely accepted and to serve universally after extending its validity to women and other age groups.

scholarly journals Physiological and Perceived Effects of Forearm or Head Cooling During Simulated Firefighting Activity and Rehabilitation

2016 ◽  
Vol 51 (11) ◽  
pp. 927-935 ◽  
Author(s):  
Susan Yeargin ◽  
Amy L. McKenzie ◽  
Lindsey E. Eberman ◽  
J. Derek Kingsley ◽  
David J. Dziedzicki ◽  
...  
Keyword(s):  
Thermal Sensation ◽  
Control Group ◽  
Control Groups ◽  
Physiological Strain ◽  
Strain Index ◽  
Head Cooling ◽  
Physiological Strain Index ◽  
Cooling Devices ◽  
Perceived Effects ◽  
And Control

Context: Cooling devices aim to protect firefighters by attenuating a rise in body temperature. Devices for head cooling (HC) while firefighting and forearm cooling (FC) during rehabilitation (RHB) intervals are commonly marketed, but research regarding their efficacy is limited. Objective: To investigate the physiological and perceived effects of HC and FC during firefighting drills and RHB. Design: Randomized controlled clinical trial. Setting: Firefighter training center. Patients or Other Participants: Twenty-seven male career firefighters (age = 39 ± 7 years; height = 169 ± 7 cm; weight = 95.4 ± 16.8 kg). Intervention(s): Firefighters were randomly assigned to 1 condition: HC (n = 9), in which participants completed drills wearing a cold gel pack inside their helmet; FC (n = 8), in which participants sat on a collapsible chair with water-immersion arm troughs during RHB; or control (n = 10), in which participants used no cooling devices. Firefighters completed four 15-minute drills (D1−D4) wearing full bunker gear and breathing apparatus. Participants had a 15-min RHB after D2 (RHB1) and D4 (RHB2). Main Outcome Measure(s): Change (Δ) in gastrointestinal temperature (TGI), heart rate (HR), physiological strain index, and perceived thermal sensation. Results: The TGI increased similarly in the HC and control groups, respectively (D1: 0.57°C ± 0.41°C, 0.73°C ± 0.30°C; D2: 0.92°C ± 0.28°C, 0.85°C ± 0.27°C; D3: −0.37°C ± 0.34°C, −0.01°C ± 0.72°C; D4: 0.25°C ± 0.42°C, 0.57°C ± 0.26°C; P &gt; .05). The ΔHR, Δ physiological strain index, and Δ thermal sensation were similar between the HC and control groups during drills (P &gt; .05). The FC group demonstrated a decreased TGI compared with the control group after RHB1 (−1.61°C ± 0.35°C versus −0.23°C ± 0.34°C; P &lt; .001) and RHB2 (−1.40°C ± 0.38°C versus −0.38°C ± 0.24°C; P &lt; .001). The physiological strain index score decreased in the FC group compared with the control group after RHB1 (−7.9 ± 1.3 versus −2.6 ± 1.7; P &lt; .001) and RHB2 (−7.9 ± 1.6 versus −3.6 ± 1.1; P &lt; .001), but no differences between groups were demonstrated for ΔHR or Δ thermal sensation (P &gt; .05). Conclusions: The HC did not attenuate rises in physiological or perceptual variables during firefighting drills. The FC effectively reduced TGI and the physiological strain index score but not HR or thermal sensation during RHB. Clinicians and firefighters should not recommend the use of HC during firefighting but can consider using FC during RHB intervals in the field.

scholarly journals The Physiological Strain Index Modified for Trained Heat-Acclimatized Individuals in Outdoor Heat

2019 ◽  
Vol 14 (6) ◽  
pp. 805-813
Author(s):  
Christopher Byrne ◽  
Jason K.W. Lee
Keyword(s):  
Heart Rate ◽  
Heat Strain ◽  
Physiological Strain ◽  
Strain Index ◽  
Marathon Race ◽  
Physiological Strain Index ◽  
C 71

Purpose: To determine if the Physiological Strain Index (PSI), in original or modified form, can evaluate heat strain on a 0–10 scale, in trained and heat-acclimatized men undertaking a competitive half-marathon run in outdoor heat. Methods: Core (intestinal) temperature (TC) and heart rate (HR) were recorded continuously in 24 men (mean [SD] age = 26 [3] y, VO2peak = 59 [5] mL·kg·min−1). A total of 4 versions of the PSI were computed: original PSI with upper constraints of TC 39.5°C and HR 180 beats·min−1 (PSI39.5/180) and 3 modified versions of PSI with each having an age-predicted maximal HR constraint and graded TC constraints of 40.0°C (PSI40.0/PHRmax), 40.5°C (PSI40.5/PHRmax), and 41.0°C (PSI41.0/PHRmax). Results: In a warm (26.1–27.3°C) and humid (79–82%) environment, all runners finished the race asymptomatic in 107 (10) (91–137) min. Peak TC and HR were 39.7°C (0.5°C) (38.5–40.7°C) and 186 (6) (175–196) beats·min−1, respectively. In total, 63% exceeded TC 39.5°C, 71% exceeded HR 180 beats·min−1, and 50% exceeded both of the original PSI upper TC and HR constraints. The computed heat strain was significantly greater with PSI39.5/180 than all other methods (P < .003). PSI >10 was observed in 63% of runners with PSI39.5/180, 25% for PSI40.0/PHRmax, 8% for PSI40.5/PHRmax, and 0% for PSI41.0/PHRmax. Conclusions: The PSI was able to quantify heat strain on a 0–10 scale in trained and heat-acclimatized men undertaking a half-marathon race in outdoor heat, but only when the upper TC and HR constraints were modified to 41.0°C and age-predicted maximal HR, respectively.

Evaluation of different levels of hydration using a new physiological strain index

1998 ◽  
Vol 275 (3) ◽  
pp. R854-R860 ◽  
Author(s):  
Daniel S. Moran ◽  
Scott J. Montain ◽  
Kent B. Pandolf
Keyword(s):  
Heart Rate ◽  
Heat Stress ◽  
Exercise Intensity ◽  
Esophageal Temperature ◽  
Sweating Rate ◽  
Physiological Strain ◽  
Strain Index ◽  
Hydration Level ◽  
Physiological Strain Index ◽  
Different Levels

A physiological strain index (PSI), based on rectal temperature (Tre) and heart rate (HR), was recently suggested for evaluating heat stress. The purpose of this study was to evaluate the PSI for different combinations of hydration level and exercise intensity. This index was applied to two databases. The first database was obtained from eight endurance-trained men dehydrated to four different levels (1.1, 2.3, 3.4, and 4.2% of body wt) during 120 min of cycling at a power output of 62–67% maximum O2 consumption (V˙o 2 max) in the heat [33°C and 50% relative humidity (RH)]. The second database was obtained from nine men performing exercise in the heat (30°C and 50% RH) for 50 min. These subjects completed a matrix of nine trials of exercise on a treadmill at three exercise intensities (25, 45, and 65%V˙o 2 max) and three hydration levels (euhydration and hypohydration at 3 and 5% of body wt). Tre, HR, esophageal temperature (Tes), and local sweating rate were measured. PSI (obtained from either Tre or Tes) significantly ( P < 0.05) differentiated among all exposures in both databases categorized by exercise intensity and hydration level, and we assessed the strain on a scale ranging from 0 to 10. Therefore, PSI applicability was extended for heat strain associated with hypohydration and continues to provide the potential to be universally accepted.

Controlled 5-mo aerobic training improves heart rate but not heart rate variability or baroreflex sensitivity

2000 ◽  
Vol 89 (5) ◽  
pp. 1825-1829 ◽  
Author(s):  
Antti Loimaala ◽  
Heikki Huikuri ◽  
Pekka Oja ◽  
Matti Pasanen ◽  
Ilkka Vuori
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Exercise Training ◽  
High Intensity ◽  
Baroreflex Sensitivity ◽  
Aerobic Training ◽  
Control Group ◽  
Resting Heart Rate ◽  
Endurance Time ◽  
Low Intensity

Endurance-trained athletes have increased heart rate variability (HRV), but it is not known whether exercise training improves the HRV and baroreflex sensitivity (BRS) in sedentary persons. We compared the effects of low- and high-intensity endurance training on resting heart rate, HRV, and BRS. The maximal oxygen uptake and endurance time increased significantly in the high-intensity group compared with the control group. Heart rate did not change significantly in the low-intensity group but decreased significantly in the high-intensity group (−6 beats/min, 95% confidence interval; −10 to −1 beats/min, exercise vs. control). No significant changes occurred in either the time or frequency domain measures of HRV or BRS in either of the exercise groups. Exercise training was not able to modify the cardiac vagal outflow in sedentary, middle-aged persons.

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