Principles of Exercise & Conditioning

Over the last 60 years, greater awareness has been given towards the therapeutic effects resistance training has on muscular functioning and physical health. Scientific exploration and investigation into physical training practices have resulted in improvements in strength, hypertrophy, and muscular endurance. However, within the weight training and athletic communities, pseudoscience has often been the primary catalyst that drives unsupported recommendations for strength development. Besides, commercial gyms provide trainees with misinformation regarding the construct of a training programme. Unsubstantiated advice is often provided to these trainees regarding what acute programme variables should be modified (i.e. repetitions, set configurations, resistance loading, inter-set recovery periods, and training frequency) that would help to develop muscular strength. As a result of this misrepresentation of evidence, the development of training guidelines has evolved from pseudoscience that guides the lay person. Fortunately, contemporary exercise physiology now ensures that greater emphasis is placed on empirical evidence that focuses on the manipulation of RT variables and the application towards strength development. Current scientific literature has advanced the development of RT programmes from the early work of the 20th century. However, the evidence on the effects of manipulating RT variables has on muscular strength is still sparse. Current RT methods and guidelines have been established without a substantial body of scientific evidence that can support these assertions.

 

Essential principles and programme variables of resistance training prescription

 

RT has grown in popularity over the last 35 years, with resistance exercise being practised as a recreational activity and to enhance athletic performance. This mode of exercise is prescribed (in part) by physicians, coaches, and exercise professionals with the premise of improving individuals’ general level of health and fitness. It has also been suggested that RT is an appropriate method to improve physiological health including increased bone density (Menkes et al., 1993), reduce pain and discomfort from arthritis (Rall et al., 1996), decrease low back pain (Nelson et al., 1995), improve glucose metabolism (Hurley, 1994), and counteract obesity (Heyward, 1998) when integrated within an exercise programme. There has also been a body of scientific evidence that has demonstrated that RT is an effective method that improves neuromuscular functioning and is applicable in the development of individual health status (Baechle and Earle, 2008). These health benefits of RT are primarily a preventative countermeasure where muscle weakness compromises optimal functioning. Resistance programmes are also used as a method that enhances athletic conditioning and performance and aids in the rehabilitation of sporting injuries (Behm and Colado, 2012).

 

The effectiveness of an RT programme depends on the careful manipulation of training variables in which to develop maximum strength (Figure 1). However, trainees of various levels and experiences expect to develop muscular strength by following generic RT programmes that are often generalised training principles. These programmes are based upon established scientific training principles and are often interpreted as the fundamental basis of developing muscular strength. Unfortunately, these training principles only serve as a starting point and provide information that applies to general health development. That said, a well-designed RT programme that is regularly performed can produce numerous benefits, including increased muscle strength, size, and alterations to body composition (Baechle and Earle, 2008). However, designing an RT programme that improves muscular strength is a complex process that incorporates several acute training programme variables and fundamental training principles (Figure 1).

 

 

 

 

 

 

 

 

 

 

 

​

Progressive Overload

 

Trainees must be exposed to an overload stimulus at regular time periods to induce strength training adaptations. Overload represents the magnitude of work required to disrupt the biological equilibrium and generate an adaptational response. RT, therefore, imposes physiological stress that disturbs the homeostatic equilibrium (Brooks et al., 2005). Acute bouts of RT result in transient physiological and metabolic changes, which then return to pre-exercise levels during the recovery period. However, if resistance exercise sessions are repeated over a prolonged period, they may induce chronic adaptations. RT can result in altered metabolism (Coyle, 2000), changes in neuromuscular recruitment patterns and remodelling of tissue (Häkkinen et al., 2003). For strength progression to occur, the physiological system must be disturbed. This overload stimulus can be manipulated by altering acute training variables (Bompa, 1999). These acute training variables include set-volume, loading, inter-set recovery, frequency, and selection and order of exercise (Bird, Tarpenning and Marino, 2005).

​

Progressive overload refers to the gradual increase in physiological stress placed on the human body during physical training (Hoffman and Ratamess, 2008). As already discussed earlier the concept of progressive overload is not original and dates back several thousand years ago to the ancient Greek strongman and Olympic wrestling champion Milo of Crotona (Figure 2). Importantly, the human body has no aspiration to become physically stronger or conditioned unless it is required to meet higher physical demands. The lack of progressive overload in a program is a prominent factor for inert development. The use of progressive overload can overcome accommodation. Accommodation is the staleness resulting from the limited adjustment in the training program (Zatsiorsky and Kraemer, 2006). Adaptations to a training program take place within a few weeks of administering. Correct manipulation of acute program variables, therefore, alters the imposed training stimulus, and if the stimulus exceeds the individual’s conditioning threshold, then further improvements in muscular fitness can occur. 

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

 

Manipulation of resistance training variables

​

Progressive overload can be integrated into any resistance training in various means. These can include: 

​

• The loading that is limited may be increased. For example, the individual may train with a higher relative percentage of their 1RM or use greater absolute loading within a continual repetition structure. For example, during weeks the initial training sessions (weeks 1-to-3) the individual trains at 70% of 1RM for several structural exercises. During weeks 4-to-5, the loading is increased by 5% to 75% of their 1RM, with a further increased in loading occurring at weeks 6-to-8 (80% 1RM).

​

• Other overload considerations are including additional repetitions. For example, individuals performing repetitions between 8-to-12RM loading range where the individual performs a set number of repetitions for an exercise. During week 1 and 2 of training, the individual lifts 100kg in the bench press for 3 sets of 8 reps. During weeks 3 and 4, the loading at 100kg is maintained but performs 3 sets of 10 reps. During weeks 5 and 6, the repetitions are further increased to 12 for 3 sets with 100kg. Once 3 sets of 12 repetitions are achieved over two consecutive sessions, the individuals increase loading and perform 8 reps and repeat the sequence.

​

• Coaches and trainers may also increase the lifting velocity with submaximal loads to increase the neural response. The intent of the individual to lift the weight as fast as possible is necessary. Because force = mass x acceleration, increasing repetition velocity (while the mass remains constant) results in higher peak force and greater strength improvement.

​

• Modifications of individuals inter-set recovery periods may enable greater loading. If considered in combination with the above approaches, increasing the rest interval will enable greater recovery between sets allowing individuals to tolerate heavier loading. 

​​

• Session and weekly training volume may be also be increased within reasonable limits (2%–5%) or varied to accommodate heavier loads (Fleck and Kraemer, 2004). From novice to intermediate training, small increases in volume have been reported to increase hypertrophy. However, some evidence suggests with further progression it is the modification of both volume and intensity that becomes critical in program design.

 

• Other training approaches have been suggested at supramaximal-loading training ranges. For example, methods such as forced repetitions, heavy negatives, partial repetitions in the strongest area of the range of motion (ROM), and variable-resistance devices have been used to load either a section of the ROM or a muscle action with greater than 100% of 1RM. It is recommended that these techniques should be used cautiously and only by experienced individuals.

 

Currently, there is limited and contradictory evidence that guides academics and fitness professionals on the effects of modifying RT variables and maximal strength development. Information is limited regarding the effects RT has on different population groups (trained, untrained, healthy adults, and older adults) and exercise selection (multi-joint and single-joint exercise). It is essential to consider that the application of different training principles and types of RT modalities can produce significant increases in strength or muscle hypertrophy if the correct ‘exercise-dose’ is applied. If each resistance exercise training session creates enough training stimulus to stress the specific muscle or muscle groups, a training effect occurs.

 

To achieve maximal results in muscular strength development, one must consider the science that has helped plan the appropriate programme structure and design. Kraemer and Ratamess (2004) state that “the act of resistance training, itself, does not ensure optimal gains in muscle strength and performance”. There have been several questions that have been proposed concerning the appropriate RT prescription that are intended to produce functional changes in muscular strength (Hass, Feigenbaum and Franklin, 2001. Currently, there is debate regarding which RT modality most effectively increases maximum strength. For example, studies have been performed on the mode of exercise (Cotterman et al., 2005), order of RT exercise (Simão et al., 2005), training frequency (Di Brezzo, Fort and Hoyt III, 2002), inter-set recovery (Henselmans and Schoenfeld, 2014), and daily training volume on strength training (Schoenfeld et al., 2016). However, of all the different RT factors, training volume, set-volume and resistance loading have received the most scientific attention.

​

Training specificity

​

The principle of training specificity requires that all training adaptations are specific to the stimulus being applied. Although in many situations general phycological improvements take place, most adaptations will be due to the specific stimuli. Training adaptations are specific to the muscle actions involved, the velocity of movement and rate of force development, range of motion, muscle groups involved, energy metabolism, movement pattern, and loading/volume of training (Kraemer and Ratamess, 2004). Specificity becomes most apparent when individuals progress to more advanced resistance training modes with several studies reporting that training effects in untrained and moderately trained individuals.

​

This training effect applies to:

​

• Strength residue from unilateral training (to the opposite limb).    

• Strength residue from the trained muscle action to an untrained action

• Strength residue from limited-ROM training to other areas of the ROM or full ROM.

• Strength residue from one velocity to another. 

• Motor performance (jumping ability, sprint speed, and sport-specific movements) improvements resulting from resistance training.

​

Variation 

​

To keep the training stimulus optimal the training variables must be modified over time. This is to create an environment that the human body has to constantly respond to and is, therefore, critical for adaptations to take place. Fleck (1994) reports that there is a large body of scientific evidence that supports the promotion of systematically varying training volume and intensity in comparison to programs that did not adopt this approach. Training sessions may be altered in a variety of ways and coaches and trainers should seek to develop a ‘toolbox’ that provides them with an array of strategies for creating progression. It is also important to understand that there is a minimum of 50 modifications that can be made to a training stimulus and as such the coach or trainer would benefit to be aware of program design variations (Figure 3).