Application of spiroergometry to determine work metabolism related strain in the course of cable work with a mini forestry crawler

ABSTRACT

Winching is a common practice for extracting logs in forest operations; however, it requires significant physical effort by humans to pull-out the cable to the felling site. The aim of this study was to quantify the intensity of this activity by measuring human effort parameters during different winching operations under experimental conditions with a mini forestry crawler. Internal energy provision was determined by a portable spiroergometric device which was linked to beat-to-beat heart rate measurement. These data as well as the pulling force were assigned to the respective distance markers. After a small decrease over the first few meters, the pulling force increased as the pull-out distance increased. A maximum heart rate reserve of 67.3% and a metabolic equivalent (MET) of 11.6 were reached at the choking point in the flat winching direction. When winching was simulated uphill, peak values between 6.6 and 9.1 METs were reached at the end of the winching process. Winching with a remote-controlled mini forestry crawler over a distance of 50 m was rated as vigorous work, since METs of 6.0 for the entire work cycle were frequently exceeded. Thus, winching distances should be kept shorter in order to reduce metabolic strain. Moreover, winching teams should take active breaks and rotate work tasks during the working day to enable the necessary recovery.

KEYWORDS:

• Winching
• log extraction
• spiroergometry
• pulling force
• work fatigue

Author Contribution

F.B., S.H. conceived, designed and performed the experiments with contributions from S.P.; F.B. and S.H. analyzed the data; F.B. and S.H. wrote the paper with contributions from D.J., S.P. and J.S.

Acknowledgments

The authors want to thank Mr. Fernando Rossi and Mrs. Marie Klein for their technical support, the Forstrevier Todtnau, as well as “F hoch 3 – Forstbetrieb” and the test persons for participation in the field trials. We also acknowledge the valuable comments of the two anonymous reviewers and the editor in charge.

Dr. Janine Schweier changed affiliation. She is now teamleader of the research group ‘research group Sustainable Forestry’ at the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL).

Disclosure Statement

The authors declare that they have no competing interests.

Notes

1. Also referred to as ergospirometry.

2. HR_max calculation based on the common formula: 220-age of the subject (Robergs and Landwehr 2002).

Additional information

Funding

This work was supported by the GFH—Gesellschaft zur Förderung der forst- und holzwirtschaftlichen Forschung an der Universität Freiburg im Breisgau e.V.; by the Federal Ministry of Food and Agriculture (BMEL) and the Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety (BMUB) within the framework of the “Förderrichtlinie Waldklimafond” (Grant 22WB304801); J.S. was supported by the European Social Fund and by the Ministry of Science, Research and Arts Baden-Württemberg.