Norvell, N., and Belles, D. (1993). Psychological and physical benefits of circuit weight training in law enforcement personnel. Journal of Consulting and Clinical Psychology, 61, 520-527.
Regular exercise is believed to result in improvements in psychological functioning; however, previous research conducted to validate this belief has produced ambiguous findings. Many studies have suggested that regular exercise can improve self-reports of depression and anxiety in both clinical and non-clinical populations. Unfortunately, according to Norvell and Belles, these studies did not employ proper controls (unbiased selection of participants, random assignment to conditions, conditions consistent in experimental demand, specific reporting of protocols employed, appropriate dependent measures, and adequate sample sizes), and as such the relationship between exercise and mental health could not be described as causal.
In addition, many researchers have attempted to determine what type of exercise produces these beneficial changes. According to the authors of this study, past research shows that the underlying psychological mechanisms that account for the beneficial effects of exercise are varied, and are not unique to aerobic training as some have suggested. As such, many different types of exercise can have psychological benefits.
Despite these benefits, past research also suggests that many people fail to complete their exercise programs. Dropout rates are surprisingly high, with as many as half of an exercise program's participants leaving within 6 months of the program. Factors contributing to this high dropout rate are being overweight, depression, low motivation, lack of spousal support, inconvenient exercise facilities, and lack of reinforcement.
One of the most stressful occupations today, according to the authors of this study, is law enforcement. Many law enforcement personnel are included in stress management interventions, and they may report feelings of helplessness and uncontrollability as sources of their stress. As a result, many law enforcement agencies have implemented exercise programs, not only to enhance those physical abilities required by officers, but also to enhance officer health and reduce the impact of stress. Such programs have been shown to improve specific physical and job performance measures, but very few studies have evaluated their effects in terms of psychological benefits. As such, the authors of this study felt it was important to examine a plethora of potential psychological benefits of exercise programs.
This study sought to evaluate circuit weight training in a population of law enforcement personnel. To avoid methodological problems discussed earlier, the authors employed an experimental design and examined the effects of the weight training program across a range of cardiovascular and strength scales. In addition, the study examined the effects of this exercise program on self-reported measures of stress, depression, anxiety, physical symptoms, and job satisfaction. According to the authors of this study, this was one of the first evaluations of the effects of circuit weight training in terms of psychological benefits.
The authors hypothesized that non-aerobic circuit weight training would result in an improvement in mood, physical condition, job satisfaction, and perceived stress. They also hypothesized that dropouts from the exercise program would be predicted by high psychological distress before the program began, and that these dropouts would be significantly more anxious and depressed than those participants who remained in the exercise program.
Norvell and Belles studied 43 male state law enforcement officers with a mean age of 32.84 and an average length of employment of 8.56 years. Of all of the participants, 81 percent were married, 85 percent were White and 30 percent were smokers. In addition, none of the participants had been involved in a regular exercise program in the previous year, none had a history of cardiac disease or orthopaedic injury that would prevent them from participating, and all of the participants were willing to abstain from exercise outside of that prescribed during the study, as were the criteria for selection for this study. …