The First Lactate Threshold Is a Limit for Heavy Occupational Work
Long-term heavy physical work often leads to early retirement and disability pension due to chronic overload, with a need to define upper limits. The aim of this study was to evaluate the value of the first lactate threshold (LTP<sub>1</sub>) as a physiological marker for heavy occupatio...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2020-08-01
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| Series: | Journal of Functional Morphology and Kinesiology |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2411-5142/5/3/66 |
| Summary: | Long-term heavy physical work often leads to early retirement and disability pension due to chronic overload, with a need to define upper limits. The aim of this study was to evaluate the value of the first lactate threshold (LTP<sub>1</sub>) as a physiological marker for heavy occupational work. A total of 188 male and 52 female workers performed an incremental cycle ergometer test to determine maximal exercise performance and the first and second lactate (LTP<sub>1</sub>; LTP<sub>2</sub>) and ventilatory thresholds (VT<sub>1</sub>; VT<sub>2</sub>). Heart rate (HR) recordings were obtained during one eight-hour shift (HR<sub>8h</sub>) and oxygen uptake was measured during 20 minutes of a representative work phase. Energy expenditure (EE) was calculated from gas-exchange measures. Maximal power output (P<sub>max</sub>), maximal oxygen consumption (VO<sub>2 max</sub>) and power output at LTP<sub>1</sub> and LTP<sub>2</sub> were significantly different between male and female workers. HR<sub>8h</sub> was not significantly different between male and female workers. A significant relationship was found between P<sub>max</sub> and power output at LTP<sub>1</sub>. HR<sub>8h</sub> as a percentage of maximum HR significantly declined with increasing performance (P<sub>max</sub>:r = −0.56; <i>p</i> < 0.01; P<sub>LTP1</sub>:r = −0.49; <i>p</i> < 0.01). Despite different cardio-respiratory fitness-levels; 95.4% of all workers performed their usual work below LTP<sub>1</sub>. It is therefore suggested that LTP<sub>1</sub> represents the upper limit for sustained heavy occupational work; which supports its use to determine work capability and assessing the limits of heavy occupational work. |
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| ISSN: | 2411-5142 |