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When designing a strength training program an often forgot yet very important aspect of success is recovery between exercise sessions. Recovery is just as important to the growth process as the actual act of muscle contraction (lifting weights). Recovery is the essential step that allows for the body to adapt and grow once stimulated to do so during the actual training bout. The question is how many days must elapse between workouts to allow the body to not only compensate for the demands of the workout, but also to overcompensate by increasing strength and muscle mass.
Gym lore tends to deal in threes. Three sets per exercise, of three different exercises, for three training days per week. This is mostly done as a means of simplifying a routine to allow for a set schedule and pattern of events to follow once the trainee steps into the gym for a workout. Very few people actually analyze their program and instead blindly follow the custom and ritual dictated by conventional gym wisdom. But does the body actually work in this way? Does every person recover in 48 to 72 hours? Does the body actually calendar the 7 day week and recover in accordance to the schedules we have arbitrarily assigned as necessary to our daily lives? Does every person at every age recover at the same rate as everyone else? Does the intensity or volume of exercise affect the duration of recovery? What is the proper way to gage the number of days between lifting sessions? Does science have any insight into the above questions and if so what are the answers? The answer, you will be relieved to find, is yes on all accounts.
In a previous article I addressed the question of how many sets should be carried out for each exercise. The research has shown that in most cases one set of exercise taken to momentary concentric (lifting phase) failure was as productive or more productive then 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 being the case, a properly conducted strength/size routine should be centered on a single set of each exercise taken to momentary concentric muscular fatigue. The frequency with which each exercise session is carried out varies according to several innate and outside influences. 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 was 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). Research carried out by the Med-X 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). Keep in mind these training sessions consisted of only training the targeted muscle group, with no other muscles being trained, for a single set to concentric failure. 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). A study ran in 2001 found 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. There also is a great disparity between people when it comes to recovering from a bout of strength training with some requiring 3 days and others requiring 4 or more days to recover from a hard training session. Another study carried out at Nautilus North in Bracebridge, Ontario Canada found that it took the average trainee seven days to recover and grow from a single session of high intensity exercise. Further 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 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.
The intensity of muscle contraction also plays a role in the recovery process. Research carried out by Howell, Chleboun, and Conaster (1993) found that following a single bout of three sets of full negative training for the biceps muscles recovery took over 6 weeks! Twelve weeks post training session a 5% strength increase was noted for the biceps in all participants. Full negative training is thought to be much more intense than standard strength training causing a deeper inroad into the bodies 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). 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 lifting 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 effecting 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. 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 no movement at all, 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 that any exercise carried out for the purpose of safe maximum muscle contraction should involve slow lifting speeds and an emphasis on both the isometric and negative portions of the repetition.
From the overwhelming amount of research some guidelines can be established to help those seeking a stronger, more muscular, fit body. The first is to train intensely, slowly, and with good form. The second is to keep the volume of training low, which in most cases means doing no more than one set per exercise. Thirdly, realize 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 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 outside influences. You should not get caught up in training a certain amount 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.
