HEAVY DUTY™ - Is it Really Based on Science?

Shane Provstgaard, Masters Degree in Exercise Science
(17 Years Experience as a High-Intensity Trainer)

HEAVY DUTY™, High-Intensity Training, Mike Mentzer -- Say any of these names in the presence of any seasoned strength trainer, and you will undoubtedly get a strong response. While the opinions - either for or against - run deep, what can be said of the science that backs High-Intensity Training? Is there enough to lend any support to Mike Mentzer’s claims of brief and infrequent training? Is there any research that supports the need of training to failure, of doing only one set per exercise, of backing off the frequency of training in accordance to the intensity of the muscular contraction? Much research has been done over the last several decades in the realm of strength training. Does any of it support HEAVY DUTY™?

One of the first and most controversial aspects of HEAVY DUTY™ training is its emphasis on single sets of each exercise. Volume proponents decry the low volume of training prescribed by HIT in general and HEAVY DUTY™ in particular. Because of the popularity of volume training, many are swayed to believe that the methodology of more is better must be correct. After all, the muscle magazines and the champions espousing these claims can’t be wrong can they? What does the research say? In study after study, one set of exercise taken to momentary concentric failure has been shown to be as productive or more productive than training with multiple sets of the same exercise (Carpinelli and Otto, 1998; Ostrowski, K.J., et al., 1997; Fincher G. E., 2000; Hass, C. J., Garzarella, L, de Hoyos, D., & Pollock, M. L., 2000; Fincher, G. E., 2001; Wolfe, B. L., Vaerio, T. A, Strohecker, K., & Szmedra, L., 2001; Journal of Exercise Physiology online, 2004). This is not to say that there has not been research to back multiple sets, but in many cases, the research has been poorly run or had confounding variables that brought the results under scrutiny (Journal of Exercise Physiology online, 2004). This being the case, most of the credible research points to the superior efficacy of a high intensity routine based on single bouts of exercise taken to momentary muscular failure. As one of the main premises of HEAVY DUTY™ is the tightly regulated use of set volume, HEAVY DUTY™ is backed by science. Mike Mentzer believed that the greater the volume of sets in a workout, the longer it would take just to recover from the exercise leaving less of the body’s resources for growth. A study ran in 2001 found this to be true, finding that multiple sets carried to failure can result in extended recovery times of 96 hours or longer just to recover to pre-exercise strength (McLester, J. R., Bishop, P, Smith, J., Dale, B., & Kozusko, J., 2001). Some of the participants in the study had not recovered pre-workout strength even at the last testing of 96 hours (4 days) post-exercise session. It seems that the more sets added to the routine, the longer the window for recovery. This study also found that people recovered at different rates. Mike Mentzer was aware of this and HEAVY DUTY calls for the regulation of volume, frequency, and intensity of training based on each person’s innate response to exercise.

Another controversial issue when dealing with HEAVY DUTY™ is the frequency with which it is carried out. Mike Mentzer was a staunch advocate of doing not less, not more, but the precise amount of strength training needed to elicit the maximum physiological response. Research on this aspect of strength training has been sorely overlooked by the exercise science community. What little that has been done has shown that a frequency of once to twice per week, or less, was as effective as training for three or more sessions per week. Studies regarding the muscles of the lumbar area (lower back) have shown that training frequencies of once per week to once every other week were as productive in the acquisition of lumbar muscle strength as training frequencies of 2 to 3 times per week (Carpenter et al., 1991; Graves et al., 1990). Once the strength of these muscles improved, the increased strength could be maintained with but one set of 8 to 10 repetitions every two to four weeks (Tucci et al., 1992). The muscular rotators of the hip area have shown similar strength gains when training at 2 days per week as opposed to 3 days per week (DeMichele et al., 1997). Training once per week with one set also resulted in impressive gains in muscular strength for the cervical spine (Highland, R.H., Vie, L. L., Dreisinger, T. E., Russell, G. S., 1992). Research carried out by the MedX Corporation on quadriceps training via a leg extension machine showed a 60% to 80% increase in quadriceps strength with training frequencies of once per week or less (Jones; et al., 1993). The take home message of all of this research is that even with one set of one exercise once or twice per week participants were able to gain strength and hypertrophy. In older adults training just once per week with a single set high intensity routine resulted in the same strength gains as training twice per week (J DiFrancisco-Donoghue, W Werner, P C Douris, 2007).

With HEAVY DUTY™ high-intensity training, the frequency of training is adjusted to the individual. Again, as with the other precepts of HEAVY DUTY training, the research bears this out. A study carried out at Nautilus North in Bracebridge, Ontario, Canada found that although it took the average trainee seven days to recover and grow from a single session of high intensity exercise some participants required nine to eleven days to recover and grow from one training session (Little, 2006). This study backed up the findings from the previously cited study (McLester, J. R., Bishop, P, Smith, J., Dale, B., & Kozusko, J., 2001) showing that the optimal recovery interval between hard training sessions is much longer than previously thought and that people recover at different rates, some taking much longer than others.

HEAVY DUTY™ also calls for the judicious use of advanced high-intensity techniques and then only within the parameters of a tightly regulated routine. Full negative training is one such form of advanced HEAVY DUTY training, and the research regarding its use has shown that extended periods of recovery are necessitated following its use. Howell, Chleboun, and Conaster, (1993) found that recovery following a single bout of three sets of full negative training for the biceps muscles required over 6 weeks! Once recovered, the biceps for all participants averaged a 5% increase in strength at a full twelve weeks post training session. Full negative training is thought to be much more intense than standard strength training causing a deeper inroad into the body’s limited recuperative resources necessitating longer recovery times. Further research into the effects of multiple sets of extremely intense negative contractions noted similar decreases in strength following the training session with the corresponding exaggerated recuperative times (Jones, Newman, Round, and Tolfree, 1986; Newman, Jones, and Clarkson, 1987; and Ploutz-Snyder, Tesch, and Dudley, 1998). Because of the extreme nature and inroading of advanced HEAVY DUTY™ methods, such as full negative training, Mike Mentzer only allocated their use for advanced HEAVY DUTY™ practitioners that have mastered the fundamentals of HEAVY DUTY and that are reaching the end of their genetic potential.

Another study employing a single set of concentric/eccentric (negative) or concentric/ accentuated eccentric (negative) training for the knee extensors found that two sessions per week for 10 weeks resulted in roughly a 100% improvement in strength (Godard, Wygand, Carpinelli, Catalano, and Otto, 1998). Keep in mind that was one total set of exercise per workout twice per week. Judging from the aforementioned research, multiple sets even for different body parts would likely add to the time necessary for full recuperation from the training session, as the added volume would cause deeper inroads with each successive set. It might seem from the above data that training with less intensity, but with more volume may allow for a more frequent and productive routine, but the research supports intensity, leading to muscular failure, above all else when it comes to producing strength and hypertrophy (Bigland-Ritchie, Furbush, & Woods, 1986; Rooney, Herbert, & Balnave, 1994; Drinkwater et al, 2005). As a case in point, the above cited research involving concentric/eccentric training noted a 100% or greater increase in strength over 10 weeks, whereas a review of 12 other studies employing less intense but more frequent modalities of strength training noted only a 7% to 71% increase in strength over a period of time ranging from 8 to 24 weeks of training (Fleck & Kraemer, 1987).

Another factor affecting the amount of force production produced by the muscles contractile components (muscle fiber) and therefore, the intensity of each exercise, is the rate of speed with which the weight is actually lifted. HEAVY DUTY training calls for the execution of each repetition in a slow controlled manner. Biomechanists have found that the only time a muscle builds maximum contractile force is at zero velocity (Hamill & Knutzen, 1995). Further research has found that lifting at high velocities (explosive lifting) did not result in higher levels of muscle fiber recruitment (Burhle, Schmidtbleicher, and Russel, 1983), but can precipitate the onset of spondylosis as well as expedite bone and joint damage (Dangles & Spencer, 1987). Research has also found that lifting at slow speeds, or with minimal movement (isometric training), results in greater strength and muscle mass gains than standard lifting techniques or even other high-intensity techniques (Westcott, W. L., Winett, R. A., Anderson, E. S., Wojcik, J. R., Loud, R. L., Cleggett, E., & Glover, S., 2001; Little, 2006). Because force production and intensity of muscle contraction are dictated by slow controlled movement, it is imperative, as Mike Mentzer stated, that any exercise carried out for the purpose of safe maximum muscle contraction should involve slow controlled lifting speeds consisting of a 4 second concentric phase, a 2 second pause in the fully contracted portion of the exercise, and a 4 second eccentric phase.

From the overwhelming amount of research, Mike Mentzer and his HEAVY DUTY™ style of high-intensity exercise established safe effective guidelines for those seeking a stronger, more muscular, fit body. The foundation of the HEAVY DUTY™ training system is to train intensely, slowly, and with good form, while keeping the volume of training low, which means doing no more than one set per exercise. He also realized that the strength training process is tri-phasic in nature, meaning you must first stimulate the muscle to grow, then you must recover from the training bout, which can take anywhere from 24 to 264 hours or more to accomplish, and only then can your body actually strengthen and grow from the training session. The recovery rate or period of time between training bouts is highly personalized, meaning you should not let gym dogma and custom dictate your training program. Remember, as per Mentzer, that training before you have recovered fully will not allow you to actualize the growth production stimulated from your training routine. Also, remember that the frequency of training can change as you get older, the intensity of your training goes up (which could be related to you getting stronger [more muscle mass being recruited] or adding intensity variables), or any other number of innate or external influences. You should not get caught up in training a certain number of days per week, but instead should be tracking your strength gains with a log book and adjust your frequency of training until strength gains are noted on the exercises you are performing. Again, the research has shown that exercise should be looked at in terms of performing the minimal dose to achieve the maximum benefit. This will limit the wear and tear on the body, allow for maximum recovery, and this, when combined with a proper diet and sleep will result in the greatest strength and hypertrophy gains allowed by your individual genetics.

--- M. Shane Provstgaard, M.Sc.

[Ed.: Shane Provstgaard is a trainer specializing in High-Intensity Training. He holds both Bachelors and Masters degrees in Exercise Science and has 17 years experience training a wide variety of clients ranging from teenagers looking to improve their sport to post-stroke patients looking to regain the strength and fitness necessary for everyday life.]
© Copyright 2011 – SHANE PROVSTGAARD –


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