The First Lactate Threshold Is a Limit for Heavy Occupational Work.

Area of Science:

• Occupational Health
• Sports Physiology
• Ergonomics

Background:

• Heavy physical work can lead to chronic overload, early retirement, and disability pensions.
• Establishing physiological markers to define upper limits for heavy occupational work is crucial.
• The first lactate threshold (LTP₁) is a potential physiological marker for assessing work capacity.

Purpose of the Study:

• To evaluate the utility of the first lactate threshold (LTP₁) as a physiological marker for heavy occupational work.
• To determine the relationship between LTP₁ and occupational work capacity.

Main Methods:

• 188 male and 52 female workers underwent incremental cycle ergometer tests to determine maximal exercise performance and lactate thresholds (LTP₁, LTP₂) and ventilatory thresholds (VT₁, VT₂).
• Heart rate (HR) was recorded during an eight-hour work shift (HR_8h).
• Oxygen uptake and energy expenditure (EE) were measured during a representative work phase.

Main Results:

• Significant differences in maximal power output (P_max), maximal oxygen consumption (VO_{2 max}), and power output at LTP₁ and LTP₂ were observed between male and female workers.
• Heart rate during an eight-hour shift (HR_8h) did not differ significantly between genders.
• 95.4% of all workers performed their usual work below their LTP₁, irrespective of fitness levels.

Conclusions:

• The first lactate threshold (LTP₁) appears to represent the upper physiological limit for sustained heavy occupational work.
• LTP₁ can be utilized to assess work capability and define the limits of strenuous occupational tasks.
• This finding supports the use of LTP₁ in occupational health assessments to prevent chronic overload and related disabilities.