Physically demanding jobs help boost worker fitness

Findings apply mainly to younger workers

A study concluding that physically demanding jobs boost the physical fitness of workers might not open many eyes, but a glance below the surface of a recent article may provide some valuable insights for occupational health professionals. The study, published in the January 2002 issue of Medicine & Science in Sports & Medicine, the monthly journal of the Indianapolis-based American College of Sports Medicine, looked at nearly 8,500 individuals in Finland. It showed that young men who were engaged in heavy physical work had higher levels of cardiorespiratory fitness, hand-grip strength and trunk muscle endurance than young men who did lighter work. The study found similar results in cardiorespiratory fitness for women. Frequent leisure-time activity was also associated with better results in the step and trunk extension tests, but not in the handgrip test.1

Older workers pay a price

Interestingly, the study also found that physically demanding jobs are not nearly so beneficial for older workers. In fact, middle-aged workers in physically demanding jobs were actually found to have lower fitness than workers who engaged in less strenuous work. "Certainly, training benefits can be derived from physically demanding occupations," notes Bradley C. Nindl, PhD, FACSM, CPT, MS, research physiologist in the military performance division of USARIEM in Natick, MA. "But the article also finds that with older workers, increased physical occupational demands may be detrimental to fitness. This finding raises important questions regarding short-term vs. long-term effects of physically demanding jobs."

One reason for this variance, Nindl offers, may be the fact that the occupational physical demands of any given job are usually absolute and not based on age or gender. "To use a military example, a soldier deployed to the field must carry a mandated list of items and equipment in a rucksack and thus all soldiers will carry the same load, no matter what their physical capacities are," Nindl offers. "Similar analogies would apply for industry. With the aging process comes diminished physical capacities, yet the occupational requirements remain the same."

Possible explanations

This scenario, he points out, is likely to lead to overuse syndromes and injuries due to a mismatch between personnel capacity and job demands. "Also, perhaps the fatigue from the daily grind leaves one less likely to seek out leisure time physical activity," he suggests. "These could be partial explanations for the finding of the age difference in the relationship between fitness and daily work."

Some of these differentials may be overcome with special training. For instance, in an article published last year in Medicine & Science in Sports & Medicine, Nindl and colleagues found that gender differences in physical performance measures were reduced after resistance training in women, which underscores the importance of such training for physically demanding occupations.

Job analysis a must’

Similarly, a job analysis is essential when screening applicants, says Nindl. "You must consider what the requisite energy systems, muscle groups, and movements for the job are," he advises. "The goals or desired outcome variables can then be identified. An office worker would benefit from a generalized fitness program, with perhaps no need for task specific training, other than taking proper workplace preventive measures for CTDs [cumulative trauma disorders]," he suggests. "Physically demanding jobs can benefit from structured fitness programs designed to improve the fitness components most important for job success."

For more information, contact: Bradley C. Nindl, PhD, FACSM, CPT, MS, Research Physiologist, Military Performance Division, USARIEM, Natick, MA 01760. Telephone: (508) 233-5382. Fax: (508) 233-4195. E-mail: Bradley.Nindl@NA.AMEDD.ARMY.MIL.

References

1. Tammelin T, Nayha S, Rintamaki H et al. Occupational physical activity is related to physical fitness in young workers. Med Sci Sports Exerc 2002; 34:1; 158-166.

2. Kraemer WJ, Mazzeti SA, Nindl B et al. Effect of resistance training on women’s strength/power and occupational performances. Med Sci Sports Exerc 2001; 33:6, 1,011-1,025.