Resistance training (RT), also commonly referred to as strength training or weight training, is a form of anaerobic exercise that utilizes external resistance of varying loads to improve musculoskeletal fitness. Compared with aerobic exercise, there are significantly more variables to consider when structuring an appropriate RT bout or program. Some of these prescription considerations include repetitions, sets, load, rest intervals, exercise order, speed of movement, body part training split, and frequency. Also, unlike aerobic exercise, RT volume is not time-dependent but rather a function of repetitions x sets. Dumbbells, machines, resistance bands, free weights, and body weight can be successfully employed to provide resistance and overload. When applied correctly, RT causes increases in muscular strength, hypertrophy, and endurance. RT has also been used clinically to positively influence such conditions as arthritis, Type II diabetes, and musculoskeletal dysfunction and injury. RT is also particularly appropriate for older adults, as it reverses the typical age-related sarcopenia and consequent loss of strength. It has also become increasingly apparent that RT can impact psychological outcomes in addition to physiological outcomes. For example, RT has been linked with improvements in depression, anxiety, positive and negative affect, self-efficacy, cognition, and quality of life (QOL).
Resistance Training and Affective Responses
Much of the early work in this area found that acute RT resulted in either elevations or little to no change in state anxiety (SA) responses, suggesting that this was an inferior form of exercise for improving mental health in comparison to aerobic exercise. However, a number of studies have since observed improvements in SA and other relevant psychological outcomes. It appears that factors such as the type of RT routine performed, training load, and intensity influence the psychological responses accompanying acute RT.
Altering the RT load can significantly affect the acute metabolic, autonomic, and hormonal responses to training. Consistent with these responses, a growing number of investigations have documented improvements in psychological states following acute bouts of RT incorporating light to moderate training loads. Unfortunately, most of the prior investigations had notable differences in load determination and assignment, total volume, repetition ranges, and rest intervals between sets. This has made drawing conclusions regarding the dose–response relationship between acute RT and psychological responses difficult. Additionally, most of these studies have focused primarily on anxiolytic effects of exercise. However, a recent well-designed dose–response study has demonstrated that a moderate-intensity RT bout (70% of 10 repetition maximum [RM]) produces improvement in SA, positive and negative affect, perceived energy, and calmness. Similar to what has been seen for moderate-intensity aerobic exercise, these responses appeared immediately following the moderate-intensity RT bout and persisted for at least an hour post-exercise. It is important to note that high-intensity RT (100% of 10 RM taken to momentary muscular failure) can produce unfavorable psychological responses, including increases in SA, negative affect, and tension. When properly defining intensity and controlling for RT volume, acute moderate-intensity RT results in more favorable psychological responses relative to either low or high-intensity bouts of RT. Many aspects of the RT stimulus other than load (i.e., inter-set rest intervals, volume, set termination criteria: volitional fatigue versus momentary muscular failure) directly influence RT intensity. A modification of these programmatic factors likely has a meaningful impact upon the psychological responses to acute RT.
To adequately understand the expected outcomes of a RT bout and provide an effective prescription, it is imperative that the mechanisms underlying the acute RT-affect relationship be identified. Although several biological and psychological hypotheses have been proposed to explain the mental health outcomes associated with acute exercise, empirical support has been equivocal. There is, however, increasing evidence that the hypothalamic-pituitary adrenal (HPA) axis may play a pivotal role in influencing responses to different exercise intensities. For example, cortisol and corticotropin-releasing hormone (CRH) have been found to produce anxiogenic responses with central administration. Activation of the stress response could very well explain many of the early findings in this area that suggested that RT may produce psychological disturbances. Increased CRH and cortisol levels have been associated with negative affect.
Resistance Training and Well-Being
RT programs have been found to positively impact QOL in various populations, including older adults as well as individuals who are depressed, sedentary, chronically ill, or overweight. It is likely that the greater physiological gains that would result from longer RT programs emphasizing strength or hypertrophy could translate to improved activities of daily living (ADL), thus producing greater improvements in QOL.
The psychological benefits of a RT program also exist for normal and overweight adolescents. Compared to a traditional physical education (PE) program, 12 weeks of moderate to high-intensity RT produced significant improvements in total physical self-perception, physical condition, body attractiveness, and global self-worth. These psychological outcomes were related to the significant strength gains and improvements in body composition seen with RT.
There is increasing evidence that RT may also favorably impact cognitive function. However, it appears that program length is a critical factor, with protocols longer than 6 months generally needed to produce significant improvements in cognition. This effect is seen for both moderate and high-intensity RT programs. This is clearly an area that warrants further investigation.
RT prescription for optimal mental health benefits may not be the same prescription for optimal physical benefits. However, these outcomes are not necessarily mutually exclusive, particularly when applied to training programs rather than acute exercise. Changes in musculoskeletal fitness appear to be related to positive changes in wellbeing and self-perception. Moderate-intensity RT also appears to effectively improve acute affective states. Furthermore, there is good preliminary support for the role of the stress response as a potential mechanism for affective changes. The efficacy of both acute and chronic RT is seen across many populations but appears to be particularly pronounced for individuals that potentially have the most to gain from a functional standpoint. Despite some inconsistencies in the current literature, it is apparent that this modality of exercise has the potential to positively impact a number of psychological constructs and is a useful tool for improving both physical and mental health.
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- Velez, A., Golem, D. L., & Arent, S. M. (2010). The impact of a 12-week resistance training program on strength, body composition, and self-concept of Hispanic adolescents. Journal of Strength and Conditioning Research, 24, 1065–1073.