Nonlinear Versus Linear Periodization Models

A COMMON PERMUTATION OF periodization is the undulating (nonlinear) model in which training resistance, among other variables, is acutely varied by workout (daily) or by microcycle (weekly). In contrast, the classical (linear) model generally takes a more direct approach in which training volume is steadily decreased while intensity is increased until the time of a major competition (Fleck & Kraemer, 1997). Some proponents of the undulating model believe that “light” workouts, often requiring approximately 30–65% 1RM (1 repetition maximum), allow sufficient recovery between similar training sessions while preventing detraining (Bompa & Cornacchia, 1998). Certain strengthtraining authorities speculate that during light workouts the slowtwitch (ST) muscle fibers will be exercised while the fast-twitch (FT) fibers are afforded the extra rest they may require, thus preventing overtraining. Nevertheless, caution is still advised regarding the possiblity of overtraining while using the undulating model due to the relatively high daily training intensities characteristic of advanced athletes (Wathen, Baechle, & Earle, 2000). Moreover, the idea of exclusive fiber type recruitment is unfortunately at odds with much scientific data. According to numerous studies employing electromyography (EMG) with dynamometry, force production strategy varies widely throughout various muscle groups. Large muscles primarily use increased recruitment, whereas smaller muscles use a rate coding (firing frequency) strategy. Thus, some muscles recruit most motor units even during performance of relatively light effort (e.g., 50% maximum voluntary contraction [MVC]). The deltoid and brachialis have been reported to recruit nearly all muscle fibers by approximately 70–80% MVC (Basmajian & De Lucca, 1985), demonstrating that FT motor units begin recruitment well below 70% MVC. Small muscles may therefore be at increased risk for overtraining despite the implementation of light workouts because many FT fibers are recruited even with light resistance. At least 5 glycogen utilization studies have shown energy depletion in FT fibers during low-intensity contractions. For example, Tesch et al. (1998) showed that 5 subfailure sets of 10 reps at just 45 and 60% of the 1RM resulted in significant reliance on FT motor units. This evidence, like the EMG data, indicates that a broad spectrum of muscle fibers are taxed even during low-intensity training sessions. Therefore, the contribution of light training to rest and recovery is highly suspect. One frequently cited reason for light workouts is to prevent detraining during recuperation (Bompa & Cornacchia, 1998). However, the majority of detraining data come from immobilization or aerobic studies, which cannot be extrapolated to resistancetrained individuals. Taking a day off from lifting is in no way analogous to bed confinement, weightlessness, or casting of a limb for prolonged periods. Also, immobilization studies are not typically preceded by a training stimulus, which would delay the onset of deconditioning. Detraining data of strength-trained persons are scarce, but to my knowledge there is no evidence of involution with less than 2 weeks of abstinence from resistance exercise (Hortobagyi et al., 1993), which nullifies the rationale for reduced-intensity training in a regularly executed strengthtraining program. Only one study (Baker et al., 1994) has attempted to control volume and intensity while comparPOINT/COUNTERPOINT