Abstract
Resistance training is a type of physical activity meant to improve a person’s muscular fitness by exercising a muscle against an external resistance. Besides being effective in maintaining and combatting the loss of muscle mass, resistance training is also beneficial in the prevention of osteoporosis. There are four primary objectives of resistance training exercise, namely muscular endurance, muscular strength, muscular power, and hypertrophy. With more people seeking to stay healthy and fit, research into how to benefit the most out of resistance training programs has gained momentum. The primary focus has been on the most appropriate approaches that would result in greater gains as far as the four objectives of resistance training are concerned. The current paper focused on published works that sought to investigate whether training to failure or not training to failure is the most beneficial approach to resistance training, and whether the training should be with multiple sets or single sets. The review reveals that researchers have recorded mixed findings, with some reporting that the benefits of training to failure and not training to failure are fairly the same, while others indicate that training to failure is superior to not training to failure. Similarly, it is not yet clear whether resistance training to muscle failure compared to no repetition failure is necessary when it comes to the maximisation of increases in hypertrophy as well as muscle strength.
Introduction
Over the past few years, resistance training exercises have developed to become one of the most popular training parameters for muscle growth. Coburn and Malek (2012, p.315) describe resistance training as a way of exercising muscles using opposing forces. They point out that these types of exercises are compound and multi-joint since they recruit a larger section of the body to undertake the exercise, thus, leading to the activation of more muscle fibres. The primary objectives for resistance training exercises include muscular endurance, muscular strength, muscular power, and hypertrophy. Resistance training exercises can be undertaken in either single or multiple sets. This has led to the emergence of considerable debates about which type of resistance training exercise leads to relatively more significant effects on the key primary objectives, especially muscular strength and hypertrophy. Kollias (2015) posits that many studies that sought to establish how single set exercises relate to multiple set exercises failed to consider most of the training variables constant, thus, reporting mixed findings. Haff and Triplett (2015, p.465) argue that it has come to be accepted that higher training volumes characterised by moderate to high repetition numbers per set lead to greater gains. This section reviews the findings from different studies on the effects of single sets and multiple sets of resistance training exercise on hypertrophy and muscle strength.
Resistance Training Exercises
According to Haff and Triplett (2015, p.415), resistance training describes a range of physical activities meant to improve individuals’ fitness by exercising a muscle against an external resistance. Besides being effective in maintaining and combatting the loss of the mass of muscle, resistance training is also said to be beneficial in the prevention of osteoporosis. This form of exercise can be attained through many ways, including the utilisation of traditional free weights and dumbbells, body weights, weight machines as well as medicine balls. The choice of the type of resistance technique to use depends on several factors, including individual goals, familiarity with certain exercise movements as well as the overall physical fitness (Schoenfeld et al. 2015, p.2954). For instance, individuals who are not physically fit such as the sick and aged population are encouraged to undertake machine-based exercises since they have been established to be less complex and safer compared to free weight exercises. The free weight exercises are recommended upon an increase in muscular fitness.
There are four primary objectives of resistance training exercise, namely muscular endurance, muscular strength, muscular power, and hypertrophy (Coburn and Malek 2012, p.351). Muscular strength refers to the ability of a muscle or collection of muscles to exert a maximum external force. According to Coburn and Malek (2012, p.351), this is the easiest of the four objectives to implement, and utilises relatively heavier training loads. Hypertrophy refers to the enhancement of muscle size. Training that focuses on this objective usually leads to an increase in fat-free mass and reduced percentage of body fat. On the other hand, muscular power is the highest power output that a muscle or a group of muscles can attain. Resistance training for muscular power aims at increasing the amount of work that a group of muscles can perform. Coburn and Malek (2012, p.351) argue that traditional resistance programs aimed at enhancing muscle power have been largely used among athletes. They posit that resistance training has been found to enhance the ability of athletes to exercise with less rest. Muscular endurance describes the capacity of muscles to bring about submaximal resistance repeatedly. Haff and Triplett (2015, p.465) postulate that resistance training programs focusing on muscular endurance entail performing many repetitions per set, and despite the relatively high repetition assignment, the general volume load is not exaggerated because the said loads are relatively light and the sets performed are lesser.
Different scholars have sought to establish how effective resistance training is as far as the achievement of the four objectives is concerned. Nóbrega and Libardi (2016) discuss whether resistance training to muscular failure is necessary, arguing that many fitness scholars have acknowledged resistance training as the primary method of improving skeletal muscle mass and strength. They point out that, to achieve this feat, individuals are encouraged to take up high intensity resistance training where the loads are more than 60% of a single repetition maximum. Nóbrega and Libardi (2016) describe muscular failure as the inability to set in motion a given load beyond a certain joint angle, stating that it has also been recommended as a way of maximising increases in muscle hypertrophy and strength. Through their analysis of various publications, Nóbrega and Libardi (2016) conclude that it is not yet clear whether resistance training to muscular failure is actually needed to optimise increases in hypertrophy and muscle strength compared to the absence of repetition failure.
Mangine et al. (2015, p.1) investigate the impact of training volume and intensity on muscular strength and size. They also opine that resistance training is an effective framework that facilitates the stimulation of muscle hypertrophy and improvement of muscle strength. They report that resistance training can achieve this by manipulating a variety of training variables such as intensity, order, volume, rest intervals, and frequency, which consequently impose mechanical and metabolic stresses on the muscles. Mangine et al. (2015, p.1) propose that resistance training can be viewed from two broad perspectives, namely those targeting metabolic stress and those targeting mechanical stress. They stipulate that more emphasis is placed on mechanical stress as the intensity of resistance exercise increases. On the other hand, stimulating muscle activation for training regimens that focus on metabolic stress requires a minimum intensity threshold. According to Mangine et al. (2015, p.1), combining the metabolic and mechanical stresses has been found to increase the risk of muscle damage and simultaneously increase muscle strength and hypertrophy.
Resistance training programs can be categorised further into high intensity low volume training and low intensity high volume training (Fleck and Kraemer 2014, p.22). High intensity low volume training involves maintaining the total volume per muscle group at a low level while extending sets to close to muscle failure. On the other hand, low intensity high volume training involves using several sets during exercises while avoiding muscle failure (Fleck and Kraemer 2014, p.22). High intensity low volume training can be tolerated for relatively short periods compared to low intensity high volume training. It leads to increased muscular strength in resistance training as well as the total body spread and increased anaerobic capacity in high intensity interval training (Ciccolo and Kraemer 2013, p.33). However, high intensity low volume training has been found to provide little or no improvement in aerobic capacity. On the other hand, low intensity high volume training focuses on the transportation of oxygen and the body’s oxidative metabolic systems (Ciccolo and Kraemer 2013, p.34). As such, it results in greater gains in aerobic capacity with little effect on muscular strength, anaerobic capacity, and total body spread. Studies have established that performing excessive high intensity training can result in negative impacts on adaptation because this category of resistance training has high energy demands, which consequently exert greater pressure on the glycolytic system (Price 2011, p.54). The increased pressure results in rapid depletion of muscle glycogen. The frequent attempt of high intensity training chronically depletes the muscles their energy reserves, which makes a person exhibit signs of chronic fatigue (Price 2011, p.54).