Resistance Training

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.

Conclusion

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.

References:

  1. Arent, S. M., Landers, D., Matt, K., & Etnier, J. (2005). Dose-response and mechanistic issues in resistance training and affect relationship. Journal of Sport & Exercise Psychology, 27, 92–110.
  2. Levinger, I., Goodman, C., Hare, D. L., Jerums, G., & Selig, S. (2007). The effect of resistance training on functional capacity and quality of life in individuals with high and low numbers of metabolic risk factors. Diabetes Care, 30, 2205–2210.
  1. Singh, N. A., Clements, K. M., & Fiatarone, M. A. (1997). A randomized controlled trial of progressive resistance training in depressed elders. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 52A, M27–M35.
  2. 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.

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