Danilo V. Tolusso

A Comparison of Both Motorized and Nonmotorized Treadmill Gait Kinematics to Overground Locomotion

CONTEXT Motorized treadmills (MTs) present an altered motor task compared to overground (OG) locomotion in that MT belt surfaces are motor-driven, whereas individuals walking/running OG must propel themselves. A possible solution may lie with novel nonmotorized treadmill (NMT) devices as the belt surface is propelled by the user. OBJECTIVE The purpose of this study was to compare gait performance during both MT and NMT locomotion to OG. DESIGN Crossover study. SETTING A university research laboratory. PATIENTS A total of 20 healthy adults (10 women) participated in the study. INTERVENTION Each participant performed self-selected walking and running OG, and on both an MT and NMT. MAIN OUTCOME MEASURE Shoulder, trunk, and lower-extremity kinematics were analyzed for each treadmill condition and compared to OG. RESULTS The analyses demonstrated that there were no differences between MT and OG gait kinematics during either walking or running. However, NMT gait showed increased hip, knee, and ankle flexions in late swing and early stance compared to OG during both walking and running. For example, during walking, the NMT elicited hip-, knee-, and ankle-flexion/extension angles of 34.7°, 8.0°, and 3.6° at foot strike compared to 24.8°, -3.1°, and -5.8° in the OG condition (P < .05). There was also a significant reduction in trunk-flexion/extension range of motion during running compared to OG (7.7° in NMT vs 9.8° in OG). CONCLUSIONS These differences may have implications for both training and rehabilitation on an NMT. Future studies should consider the influence of NMT familiarization on gait performance and should emphasize the assessment of neuromuscular performance.

Author’s Reply to Nunes et al.: Comment on: “Comparison of Periodized and Non-Periodized Resistance Training on Maximal Strength: A Meta-Analysis”

We appreciate the opportunity to respond to Nunes et al. [1]. The primary aim of our article [2] was to examine the current literature comparing periodized training to nonperiodized training and to quantify the effect periodized training has on 1-repetition maximum (1RM). We do not dispute Nunes et al.’s [1] argument that the principle of specificity may have influenced the strength outcomes in the studies included in our analysis. We agree that the programs utilizing greater loads will be more mechanically specific and drive adaptations for strength development. However, this concept is a central tenet of periodization. In the traditional model of periodization, training specificity gradually increases throughout the macrocycle and peaks prior to competition or testing session [3]. A program lacking training variation but adhering to the principle of specificity would require individuals to frequently train at high intensities (i.e., 1–5RM). This approach is not recommended, especially for advanced trainees, for a few reasons. First, training at high intensity for a long period of time may predispose an individual to accommodation or stagnation [4]. Variation in training loads is an important factor in breaking up the mechanical monotony that may occur during long-term linear loading [3]. Secondly, training variation is necessary for proper fatigue management [5]. Implementing ‘light’ days into a microcycle will allow for adequate volume to be achieved while also enhancing recovery efforts, which may lead to higher training intensities during the ‘heavy’ training days. Lastly, training at high intensity with low repetitions makes it difficult to accumulate adequate training volume. Advanced trainees typically require a greater amount of work performed in order to continue to develop higher levels of fitness. Variation in training allows for fluctuations in repetition ranges across a microcycle, making it easier to accumulate training volume. In a non-varied plan, more sets will need to be performed to reach a desired training volume due to the low number of repetitions completed per set. While the same volume can be achieved, training with a higher number of repetitions per set will increase the training density. Schoenfeld et al. [6] noted that a low repetition group (7 9 3RM) was able to accomplish the same volume load as the high repetition group (3 9 10RM), yet the high repetition group completed the sessions in a much shorter time than the low repetition group [6]. Varying the training loads and repetitions offers a more feasible approach to accumulating training volume, while still incorporating high-load training within a microcycle. Nunes et al. [1] noted that several of the studies included in our analysis compared a non-periodized single-set program with a periodized multi-set program. We do not disagree with their suggestion that this may have contributed to differences in strength gains. This point was identified in Sect. 4.6 as a limitation of our meta-analysis. Additionally, we performed a funnel plot and sensitivity & Tyler D. Williams twilli11@samford.edu