High Intensity Training
March 3, 2011
What the Literature Says About
High Intensity Training
by Dave Durell
The term strength training refers to a comprehensive program of exercise designed to improve the ability to produce muscular force and increase resistance to injury. Any system of such training which produces an objectively measurable increase in muscular strength can be considered productive. Beyond productivity, there are two additional factors which have been thoroughly investigated in the literature; these factors are safety and efficiency. Assuming two programs were equally productive in terms of increasing strength, logic dictates the program which was safer and more time efficient would be the superior selection. In this article, what the literature says about productivity, efficiency and safety in strength training programs will be reviewed.
Strength training has been shown to be an effective way of producing increases in muscular strength and size and decreasing body fat (Carpinelli and Otto 1998; Fleck and Kraemer 1997). Fleck and Kraemer (1997) reported that increases in lean body mass with concurrent decreases in body fat were shown in studies ranging from 6 to 24 weeks in duration (p. 155-156). These studies represented a wide variety of training protocols. Fleck and Kraemer concluded that “Because of the variation in the numbers of sets, repetitions, exercises and relatively small body composition changes, it is impossible to reach concrete conclusions concerning which program is optimal for decreasing percent fat and increasing lean body mass” (p. 154). Zatsiorsky (1995) also reported that a variety of methods are effective for increasing muscular strength.
It is universally accepted among experts in the field that a high degree of intensity of effort during strength training is required to generate increases in muscular strength (Durell 1999). Successful weight training programs are characterized by the inclusion of maximal voluntary muscular contractions at some point in the program (Fleck and Kraemer 1988). Utilizing a high level of intensity will overload a high percentage of muscle fibers; such an overload is paramount to increasing muscular strength (Kelso 1999). Carpinelli (1999) adds that recruitment of muscle fibers is primarily dependent on the intensity of exercise, not how much exercise is performed. This raises the question of how much – or more accurately, how little – exercise is required to produce results from a strength training program.
Many studies presented in the literature compared the performance of different amounts of sets of strength training exercises to determine the effectiveness of each method. A frequently cited study by Berger (1962) compared one set, two set, and three set programs using the bench press exercise with various repetition schemes. Berger concluded that three sets of six repetitions produced the best strength gains. However, subsequent studies failed to replicate these results, including a follow-up study by Berger himself (1963).
A comprehensive review by Carpinelli and Otto (1998) examined all the studies (a total of 35) which have been published, including abstracts, that reported the results of training with single or multiple sets. They concluded:
The opinion that multiple-set protocols are better than a single set of an exercise is not supported by the consensus of scientific evidence; 33 out of 35 of the comparative reports included in this review show no significant difference in strength increase between individuals performing single-set and those performing multiple-set (up to 15 sets) exercise protocols. (p. 82)
Carpinelli and Otto further conclude “There is no evidence to suggest that the response to single or multiple sets in trained athletes would differ from that in untrained individuals” (p. 82).
Other researchers have reached similar conclusions regarding the efficiency and practicality of low-volume training protocols. Starkey et al. (1994) compared strength and muscle thickness changes over 14 weeks of training using 1 set or 3 set programs. Both groups increased strength and muscle thickness with no significance between groups. The authors concluded that a 1 set training protocol was as effective as three sets and “represents a more efficient use of training time” (p. S116). Terbizan and Bartels (1984) compared the effects of 1 set versus 3 sets and high repetitions (10-15) versus low repetitions (6-9). All groups significantly increased strength with no difference between different protocols. The authors stated:
This information may be of interest to coaches determining strength training programs for their athletes, in that the same gains in strength may be accomplished in less time using 1 set vs. 3 set training and by lifting significantly less weight. (p. 267)
Assuming a strength training program has been instituted which produces increases in strength and is time-efficient, safety becomes the primary consideration.
Strength training, like any physically demanding activity, contains an element of risk of injury. The literature confirms that safety during strength training can be improved by manipulating certain variables such as exercise performance, exercise selection, equipment selection and proper supervision.
One controversial safety issue presented in the literature was the use of Olympic lifts and/or ballistic exercises in athletic strength training programs. Research by Kulund, Dewey, Brubaker, and Roberts (1978) studied the training methods and techniques of two Olympic style weightlifters and interviewed 80 competitive Olympic style weightlifters about overuse problems and injuries. The 80 lifters reported 111 injuries related to weightlifting. The shoulder and knee were the most common areas injured (p. 112). The most common duration of impairment was 2 weeks and 2 months (p.113). One of the two lifters studied fractured a rib in competition during the clean and jerk lift (p. 114). The authors concluded that most Olympic weightlifting injuries are caused by inflexibility and improper technique (p. 111).
The lumbar (lower) spine is another area which is highly susceptible to weight lifting injuries. Alexander (1985) pointed out:
This part of the body is susceptible to injury due to the large forces which must be supported, which include the body weight and any external weights, as well as the forces due to very high accelerations of the body parts. Since the lumbar spine is the only connecting column between the upper and lower parts of the body, all theforces must be transmitted via these structures. (p. 1)
Types of injuries reported to the lumbar spine included strains and sprains, disc injuries and spinal fractures(Alexander 1985). The most severe lumbar fracture injury reported was presented in a case report by Browne, Yost, and McCarron (1990). The authors described a lumbar ring apophyseal fracture which was incurred by a 16 year-old male after performing a ballistic exercise in physical education class. Only 11 cases of this particular injury had previously been reported. This 16 year-old male required 2 major back surgeries as a result of this injury. The authors concluded “Strict control of the amount of weight and types of exercises is essential” (p.535).
Other types of spinal fractures prevalent in those who perform Olympic lifts are spondylolysis, a defect of the pars interarticularis of one side of the vertebrae; and spondylolisthesis, a bilateral defect of the pars interarticularis often accompanied by a forward displacement of the vertebral body (Alexander 1985). Studies show the incidence of spondylolysis in Olympic lifters is much higher than in the general population (Jesse 1977). While referring to an article by Allman (1976), Jesse (1977) commented on the dangers of Olympic lifts and why they are included in athletic strength training programs:
Commenting on weight training programs, he claims that almost all injuries caused by exercise are the direct results of the sudden movement. Sudden lifts increase skill far more than strength, and the present confusion is probably because many strength coaches are former weight lifters themselves, he maintains. They pass on a style of training necessary for weight lifting, but neither necessary nor desirable in any other sport. (p. 65)
Other factors contributing to strength training injuries include lack of proper supervision and improper technique, which can cause both acute and chronic injuries (Reeves, Laskowski, and Smith 1998a, 1998b). Substituting machines for free weights, when feasible, can also be beneficial by increasing the stress on the target muscles, decreasing stress on the joints and increasing user confidence and safety (Friday 1999; Hay, Andrews, Vaughan, and Ueya 1983).
After reviewing the literature, some general conclusions can be drawn about strength training. First, it appears no one method of training has a monopoly on producing strength gains. In addition, most studies show single set protocols to be just as effective as multiple set protocols, with little or no significant difference between programs utilizing one to three sets per exercise. Decreased training volume can be beneficial to personal training clients, as this would leave more time available for business and leisure activities. Also, the use of Olympic lifts and/or ballistic exercises was shown to have a high potential for injury and questionable benefit to clients as compared to safer alternatives.
The rational trainer will be compelled to design the most productive, safest and most
efficient training program possible for his/her clients. Relinquishing tradition and personal bias and avoiding commercially motivated sources in favor of the scientific data found in the literature will assure such program design occurs.
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Berger, R. A. (1962). Effect of varied weight training programs on strength. Research Quarterly, 33 (2), 168-181.
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Browne, T. D., MD, Yost, R. P., MD, & McCarron, R. F., MD (1990). Lumbar ring apophyseal fracture in an adolescent weight lifter. The American Journal of Sports Medicine, 18 (5), 533-535.
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