Publications by authors named "Konstantinos Mantzios"

7 Publications

  • Page 1 of 1

Effects of Weather Parameters on Endurance Running Performance: Discipline Specific Analysis of 1258 Races.

Med Sci Sports Exerc 2021 Oct 14. Epub 2021 Oct 14.

FAME Laboratory, Department of Physical Education and Sport Science, University of Thessaly, Trikala, Greece University of Canberra, Research Institute for Sport and Exercise, Canberra, Australia Aspetar Orthopaedic and Sports Medicine Hospital, Research and Scientific Support Department, Doha, Qatar Department of Nutrition, Exercise and Sports, Section for Integrative Physiology, University of Copenhagen, Denmark.

Introduction: This study evaluated how single or combinations of weather parameters (temperature, humidity, wind speed, solar load) affect peak performance during endurance running events and identify which events are most vulnerable to varying weather conditions.

Methods: Results for the marathon, 50 km race-walk, 20 km race-walk, 10,000 m, 5,000 m and 3,000 m-steeplechase were obtained from the official websites of large competitions. We identified meteorological data from nearby (8.9 ± 9.3 km) weather stations for 1258 races held between 1936 and 2019 across 42 countries, enabling analysis of 7867 athletes.

Results: The Wet-Bulb Globe Temperature (WBGT) across races ranged from -7 to 33 °C, with 27% of races taking place in cold/cool, 47% in neutral, 18% in moderate heat, 7% in high heat, and 1% in extreme heat conditions, according to the World Athletics classification. Machine learning decision trees (R2 values: 0.21-0.58) showed that air temperature (importance score: 40%) was the most important weather parameter. But, when used alone, air temperature had lower predictive power (R2 values: 0.04-0.34) than WBGT (R2 values: 0.11-0.47). Conditions of 7.5-15 °C WBGT (or 10-17.5 °C air temperature) increase the likelihood for peak performance. For every degree WBGT outside these optimum conditions, performance declined by 0.3-0.4%.

Conclusion: More than one-quarter of endurance running events were held in moderate, high, or extreme heat and this number reaches one-half for events other than the marathon. All four weather parameters must be evaluated to mitigate the health and performance implications of exercising at maximal intensities in a hot environment with athletes adopting heat mitigation strategies when possible.
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October 2021

The Impacts of Sun Exposure on Worker Physiology and Cognition: Multi-Country Evidence and Interventions.

Int J Environ Res Public Health 2021 07 20;18(14). Epub 2021 Jul 20.

FAME Laboratory, Department of Physical Education and Sport Science, University of Thessaly, 42100 Trikala, Greece.

Background: A set of four case-control ( = 109), randomized-controlled ( = 7), cross-sectional ( = 78), and intervention ( = 47) studies was conducted across three countries to investigate the effects of sun exposure on worker physiology and cognition.

Methods: Physiological, subjective, and cognitive performance data were collected from people working in ambient conditions characterized by the same thermal stress but different solar radiation levels.

Results: People working under the sun were more likely to experience dizziness, weakness, and other symptoms of heat strain. These clinical impacts of sun exposure were not accompanied by changes in core body temperature but, instead, were linked with changes in skin temperature. Other physiological responses (heart rate, skin blood flow, and sweat rate) were also increased during sun exposure, while attention and vigilance were reduced by 45% and 67%, respectively, compared to exposure to a similar thermal stress without sunlight. Light-colored clothes reduced workers' skin temperature by 12-13% compared to darker-colored clothes.

Conclusions: Working under the sun worsens the physiological heat strain experienced and compromises cognitive function, even when the level of heat stress is thought to be the same as being in the shade. Wearing light-colored clothes can limit the physiological heat strain experienced by the body.
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July 2021

Occupational Heat Stress: Multi-Country Observations and Interventions.

Int J Environ Res Public Health 2021 06 10;18(12). Epub 2021 Jun 10.

FAME Laboratory, Department of Physical Education and Sport Science, University of Thessaly, 42100 Trikala, Greece.

Background: Occupational heat exposure can provoke health problems that increase the risk of certain diseases and affect workers' ability to maintain healthy and productive lives. This study investigates the effects of occupational heat stress on workers' physiological strain and labor productivity, as well as examining multiple interventions to mitigate the problem.

Methods: We monitored 518 full work-shifts obtained from 238 experienced and acclimatized individuals who work in key industrial sectors located in Cyprus, Greece, Qatar, and Spain. Continuous core body temperature, mean skin temperature, heart rate, and labor productivity were collected from the beginning to the end of all work-shifts.

Results: In workplaces where self-pacing is not feasible or very limited, we found that occupational heat stress is associated with the heat strain experienced by workers. Strategies focusing on hydration, work-rest cycles, and ventilated clothing were able to mitigate the physiological heat strain experienced by workers. Increasing mechanization enhanced labor productivity without increasing workers' physiological strain.

Conclusions: Empowering laborers to self-pace is the basis of heat mitigation, while tailored strategies focusing on hydration, work-rest cycles, ventilated garments, and mechanization can further reduce the physiological heat strain experienced by workers under certain conditions.
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June 2021

Environmental and Psychophysical Heat Stress in Adolescent Tennis Athletes.

Int J Sports Physiol Perform 2021 May 21:1-6. Epub 2021 May 21.

Purpose: We investigated the environmental conditions in which all outdoor International Tennis Federation (ITF) junior tournaments (athlete ages: <18 y) were held during 2010-2019. Thereafter, we performed a crossover trial ( NCT04197375) assessing the efficacy of head-neck precooling for mitigating the heat-induced psychophysical and performance impacts on junior athletes during tennis match play.

Methods: ITF junior tournament information was collected. We identified meteorological data from nearby (13.6 [20.3] km) weather stations for 3056 (76%) tournaments.

Results: Overall, 30.1% of tournaments were held in hot (25°C-30°C wet-bulb globe temperature [WBGT]; 25.9%), very hot (30°C-35°C WBGT; 4.1%), or extremely hot (>35°C WBGT; 0.1%) conditions. Thereafter, 8 acclimatized male junior tennis athletes (age = 16.0 [0.9] y; height = 1.82 [0.04] m; weight = 71.3 [11.1] kg) were evaluated during 2 matches: one with head-neck precooling (27.7°C [2.2°C] WBGT) and one without (27.9°C [1.8°C] WBGT). Head-neck precooling reduced athletes' core temperature from 36.9°C (0.2°C) to 36.4°C (0.2°C) (P = .001; d = 2.4), an effect reduced by warm-up. Head-neck precooling reduced skin temperature (by 0.3°C [1.3°C]) for the majority of the match and led to improved (P < .05) perceived exertion (by 13%), thermal comfort (by 14%), and thermal sensation (by 15%). Muscle temperature, heart rate, body weight, and urine specific gravity remained unaffected (P ≥ .05; d < 0.2). Small or moderate improvements were observed in most performance parameters assessed (d = 0.20-0.79).

Conclusions: Thirty percent of the last decade's ITF junior tournaments were held in hot, very hot, or extremely hot conditions (25°C-36°C WBGT). In such conditions, head-neck precooling may somewhat lessen the physiological and perceptual heat strain and lead to small to moderate improvements in the match-play performance of adolescent athletes.
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May 2021

Effect of a Simulated Heat Wave on Physiological Strain and Labour Productivity.

Int J Environ Res Public Health 2021 03 15;18(6). Epub 2021 Mar 15.

Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, 1000 Ljubljana, Slovenia.

Background: The aim of the study was to investigate the effect of a simulated heat-wave on the labour productivity and physiological strain experienced by workers.

Methods: Seven males were confined for ten days in controlled ambient conditions. A familiarisation day was followed by three (pre, during, and post-heat-wave) 3-day periods. During each day volunteers participated in a simulated work-shift incorporating two physical activity sessions each followed by a session of assembly line task. Conditions were hot (work: 35.4 °C; rest: 26.3 °C) during, and temperate (work: 25.4 °C; rest: 22.3 °C) pre and post the simulated heat-wave. Physiological, biological, behavioural, and subjective data were collected throughout the study.

Results: The simulated heat-wave undermined human capacity for work by increasing the number of mistakes committed, time spent on unplanned breaks, and the physiological strain experienced by the participants. Early adaptations were able to mitigate the observed implications on the second and third days of the heat-wave, as well as impacting positively on the post-heat-wave period.

Conclusions: Here, we show for first time that a controlled simulated heat-wave increases workers' physiological strain and reduces labour productivity on the first day, but it promotes adaptations mitigating the observed implications during the subsequent days.
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March 2021

A free software to predict heat strain according to the ISO 7933:2018.

Ind Health 2019 Nov 27;57(6):711-720. Epub 2019 Mar 27.

FAME Laboratory, School of Exercise Science, University of Thessaly, Greece.

Our primary objective in this study was to design and implement the FAME Lab PHS Calculator software (PHS) (, a free tool to calculate the predicted heat strain of an individual based on ISO 7933:2018. Our secondary objective was to optimize the practicality of the PHS by incorporating knowledge from other ISO standards and published literature. The third objective of this study was to assess: (i) the criterion-related validity of the PHS by comparing its results against those obtained using the original ISO 7933:2018 code; and (ii) the construct validity of the PHS by comparing its results against those obtained via field experiments performed in human participants during work in the heat. Our analysis for criterion validity demonstrates that PHS provides valid results within the required computational accuracy, according to Annex F of ISO 7933:2018. The construct validity showed that root mean square errors (RMSE) and 95% limits of agreement (LOA) were minimal between measured and predicted core temperature (RMSE: 0.3°C; LOA: 0.06 ± 0.58°C) and small between measured and predicted mean skin temperature (RMSE: 1.1°C; LOA: 0.59 ± 1.83°C). In conclusion, the PHS software demonstrated strong criterion-related and construct-related validity.
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November 2019

High prevalence of hypohydration in occupations with heat stress-Perspectives for performance in combined cognitive and motor tasks.

PLoS One 2018 24;13(10):e0205321. Epub 2018 Oct 24.

Department of Nutrition, Exercise and Sports, Section for Integrative Physiology, University of Copenhagen, Copenhagen, Denmark.

Purpose: To evaluate the prevalence of dehydration in occupational settings and contextualize findings to effects on performance in cognitively dominated tasks, simple and complex motor tasks during moderate and high heat stress.

Methods: The study included an occupational part with hydration assessed in five industries across Europe with urine samples collected from 139 workers and analyzed for urine specific gravity. In addition, laboratory experiments included eight male participants completing mild-intensity exercise once with full fluid replacement to maintain euhydration, and once with restricted water intake until the dehydration level corresponded to 2% bodyweight deficit. Following familiarization, euhydration and dehydration sessions were completed on separate days in random order (cross-over design) with assessment of simple motor (target pinch), complex motor (visuo-motor tracking), cognitive (math addition) and combined motor-cognitive (math and pinch) performance at baseline, at 1°C (MOD) and 2°C (HYPER) delta increase in body core temperature.

Results: The field studies revealed that 70% of all workers had urine specific gravity values ≥1.020 corresponding to the urine specific gravity (1.020±0.001) at the end of the laboratory dehydration session. At this hydration level, HYPER was associated with reductions in simple motor task performance by 4±1%, math task by 4±1%, math and pinch by 9±3% and visuo-motor tracking by 16±4% (all P<0.05 compared to baseline), whereas no significant changes were observed when the heat stress was MOD (P>0.05). In the euhydration session, HYPER reduced complex (tracking) motor performance by 10±3% and simple pinch by 3±1% (both P<0.05, compared to baseline), while performance in the two cognitively dominated tasks were unaffected when dehydration was prevented (P>0.05).

Conclusion: Dehydration at levels commonly observed across a range of occupational settings with environmental heat stress aggravates the impact of hyperthermia on performance in tasks relying on combinations of cognitive function and motor response accuracy.
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March 2019