Research Articles & Training Recommendations
Over the last few decades, scientific training principles have prevailed over pseudoscience and these principles are now fundamental in the development of valid RT prescription for different population ranges (Bird et al., 2005). RT is an exercise modality that is frequently recommended for different population groups (clinical, fitness and athlete) and it has been reported to improve physical health and well-being (ACSM, 2002; Kraemer, Ratamess and French, 2002). The associated health benefits for individuals performing RT cannot be underestimated. These benefits go beyond that of muscular strength and athletic performance, with the application towards muscular tension provided by RT alters and enhances an individual's well-being and longevity.
The health benefits of RT are predominantly used as a preventative training modality or as a countermeasure to conditions where muscle weakness compromise an individual's functional capacity (muscle atrophy, sarcopenia, musculoskeletal disorders or injury). It is necessary to recognise that without the body's ability to contract muscles, we could not walk, lift, breathe, digest, or perform essential biological functions. A well-conditioned muscular system enables a physically active lifestyle and enhances health factors that may reduce the risk of degenerative diseases and medical complications (ACSM, 2009). Recent evidence has suggested that muscle mass index is a stronger predictor of life expectancy than body mass index and offers additional support to the importance of muscular strength and muscle mass (Srikanthan and Karlamangla, 2014). However, during the early 20th century, misconceptions surrounded RT with the belief that it was detrimental to physical health.
Formation of Health and Fitness Organisations
The development of scientific evidence on RT since the 1940s has progressively increased with a further upsurge in magnitude throughout the 1960s and 1970s. Researchers in the 1960s refined the seminal research performed by Delorme (1945) with systematic manipulation of different RT variables from longitudinal studies (Berger, 1962; Hellebrant and Houtz 1956; Berger, 1962; Berger 1965; Capen, 1950; O'Shea, 1966). This scientific evidence and promotion of RT helped transform the landscape with increased participation and understanding of the value of RT towards physical health and well-being. This upsurge in popularity since the early 1970s has now led to national health and fitness organisations recommending that this mode of exercise be incorporated into exercise programs. These organisations included the National Strength and Conditioning Association (NSCA), the American Heart Association (AHA), the American Association for Cardiovascular and Pulmonary Rehabilitation (AACPR), Cardiovascular and Pulmonary Rehabilitation and the American College of Chest Physicians (ACCP), and the American College of Sports Medicine (ACSM) all advocated the use of RT to increase physical health, performance and longevity.
American College of Sports Medicine Position Statements
The scientific community throughout the 1970s had a limited appreciation towards the benefits of RT towards improving population-level health, except for increasing muscular strength and endurance. Some researchers believed that these functional variables played a limited role in the general population’s health. Indeed, ACSM (1978) initially produced exercise guidelines for population-level physical activity, stating that individuals need only perform aerobic exercise. This positional statement reflected the health and fitness trends and limited research on RT being performed during the 1970s. This evident lack of scientific research led to the exclusion of RT within exercise guidelines with greater importance placed on cardiorespiratory fitness and body composition. For example, epidemiological research during this period reported a strong relationship between aerobic endurance exercise and the prevention of cardiovascular disease (Fox and Skinner 1964, Kannel, 1970). This led to the significant promotion of aerobic activities to increase individuals V̇𝑂2max and was interpreted to improve physical health (Blair, LaMonte and Nichaman, 2004). Unfortunately, due to RT omission and increased promotion of aerobic exercise, some interpreted that RT was insignificant for improving physical health (Feigenbaum and Pollock, 1999).
In the early 1980s, RT was recognised as a method that could positively affect athletic performance. By the mid-1980s the medical community began to acknowledge the therapeutic value of RT on health-related aspects including low back health, weight management, bone health, and basal metabolic regulation (Feigenbaum and Pollock, 1999). The ACSM in 1990 included within its recommendations that an RT component should be incorporated within the exercise prescription for physical health and development. This acknowledgement of the therapeutic benefits of RT leads to other prominent organisations, including the AACPR, ACCP and AHA, to integrate RT within exercise programmes. This endorsement by other leading health and fitness organisations has helped to establish the ACSM as the main authoritative body of exercise prescription.
Currently, there are large volumes of published information and scientific data on RT with numerous recommendations on how to improve muscular strength across all age classifications that are founded on pre-existing literature (Table 3.0 and Figure 3.0). ACSM has published several position statements that provide recommendations for enhancing physical conditioning for specific population groups (novice to athletes). These recommendations include guidance on the resistance loading, training frequency, volume (sets x repetitions), exercise order, and exercise selection. Most novice trainees and newly qualified trainers are typically directed towards these ACSM position statements. These statements are made available via open access, and due to marketing, most individuals accept what has been published as scientifically correct and assume that the evidence has sufficiently filtered through the peer-review process. ACSM states that their guidance is the most authoritative, evidence-based statement issued by ACSM and often considered by some as definitive with suggestions that evidence is extrapolated from a large body of scientific data that provides a substantial burden of proof.
ACSM Position Statements and Training Recommendations
The ACSM and other health and fitness organisations have provided statements on strength development from as early as 1990 through to the present recommendations. The physical activity recommendations for population-level health now acknowledge the benefits of RT to improve health-related factors including, improved bone density, functional capacity, basal metabolism and back health (Feigenbaum and Pollock 1999). Consequently, health-related recommendations began to include RT within an integrated physical activity program that also included aerobic and other forms of exercise (ACSM, 1990).
The ACSM from the early 1990s emerged as the only plausible organisation that attempted to provide RT recommendations for population-level health. For example, in the ACSM (1998) position statement, “The recommended quantity and quality for developing and maintaining cardiorespiratory and muscular fitness, and flexibility in healthy adults,” provided recommendations with RT included within the program design. These suggestions encouraged individuals to perform RT with one-set of eight-to-12 repetitions for eight-to-ten exercises, including one exercise for all major muscle groups, and 10-to-15 repetitions for older adults and the infirm (ACSM, 1998). This then leads to a series of recommendations that are diversified by population group and training objectives (ACSM, 2002 and 2009).
In 2002, ACSM produced a position statement that evolved from the previous 1998 statement. These new recommendations now included guidance for those healthy adults that wish to progress their muscular fitness. The purpose of this 2002 position statement was to increase guidance from beginner RT programs to progression models that can apply to novice, intermediate, and advanced trainees. The ACSM (2009) position statement further advanced training recommendations on strength development from previous recommendations. This was generated from further studies including reviews, epidemiological studies, clinical studies, and meta-analyses on various acute RT programme variables. These new recommendations stated that novice trainees perform one-to-three-sets for eight-to-12 repetitions with 60-to-70% 1RM loading and two-to-three-minute recovery. For intermediate trainees, multiple-sets for six-to-12 repetitions at 60-to-70% 1RM and two-to-three-minute recovery. Athletes were directed towards performing multiple-sets with varying repetitions at a loading of 80-to-100% 1RM with four-to-six-minute recovery, in which to avoid over-training.
NSCA Position Statements & Articles On Physical Fitness (click image for link)
Traditionally, strength athletes only performed resistance training (RT) to improve muscle strength, power, hypertrophy, and sports-specific fitness. Unfortunately, the strength programs were established specifically from the applied experiences of the trainer or coach. This generated an explosion of unsupported RT programs that created confusion for those that were prescribed it. Indeed, RT program design was initially more of an art than science, with trainers and coaches modifying the training dose based on restricted knowledge of the physiological responses to exercise. Fortunately, in the 1960s and 1970s, American football recognised the value in RT and hired strength coaches to improve performance. By the 1970s, most strength and power athletes were performing RT. A critical development during this time was the NSCA that spread RT recommendations and attempted to disperse misconceptions and started to distribute practical and scientific evidence throughout the different sports. By the 1980s, most athletes and their coaches embedded RT for almost all sports. From the conception of this professional body, there are now over 30,000 members in 72 countries.
The NSCA have released several books and training recommendations intended for athletic development rather than universal recommendations on RT. For example, Pearson et al., (2000) produced a series of basic guidelines for RT of athletes that allowed coaches to develop athletic performance safely. These recommendations were broader ranging, unlike other organisations with programming designed specifically to match the profile of the athlete and the sport. Unlike other generic training suggestions, the approach to loading and volume is periodised to avoid the potential of over-training syndrome. The NSCA recommendations are positioned around the stress-adaptational responses and sports performance.
The NSCA specified that RT programs for athletes should be developed based on the individual needs of the athlete and specific sport. The NSCA, unlike other organisations, stated that RT programs should be developed from integrating of scientific knowledge while addressing the practical requirements of the sport. This is unlike other recommendations, as ultimately RT programming [in part] seeks to develop long-term adherence to the individualised program. This allows athletes to have programs that best meet their needs and the sport. Therefore, because of the sport, training approaches and programming draw on a broader range of knowledge and skills typically discussed in other recommendations. Strength trainers and coaches need to be creative while applying scientific knowledge to athletes’ specific needs, which is unlike the general population who have very linear goals (Kraemer, 2006).