|Weight training on separate days!?|
That's a conclusion nobody ever questioned - and that in spite of the fact that the effects of splitting strength (S) and endurance (E) training onto different days on body composition in the long term have not even been investigated, yet.
The aim of a recent study by Eklund, et al. (2016) was thus the first to investigate possible differences in body fat and lean mass, blood lipid levels and physical fitness profile following 24 weeks of volume-equated different-day and same-session combined strength and endurance training in previously untrained healthy men and women.
More specifically, this was achieved through comparing adaptations following strength and endurance training performed on different days (DD) or in the same session with two different orders (ES and SE). Ah, and yes, the recruited subjects were required not to have participated in systematic strength or endurance training for at least 1 year prior to the study. The significance of the results for trained subjects is thus not exactly clear. What is clear, however is the overall study design:
"After the basal measurements of body composition, blood lipids, maximal strength and endurance performance, each participant was randomly assigned to one of the three training modes for the entire 24-week duration of the study: 1) strength and endurance training performed on different days (DD, men n=21, women n=18), 2) strength and endurance performed in the same training session with endurance preceding strength (E+S, men n=16, women n=15) or 3) vice versa, i.e. strength and endurance performed in the same training session with strength preceding endurance (S+E, men n=18, women n=14) [...] The training program has been described in detail previously (Eklund et al. 2015). In short, the training was designed to reflect recommendations for physically active individuals as well as targeted at improving both maximal strength and endurance performance. During the initial 12 weeks, the same-session subjects completed two weekly sessions of [1E+1S] or [1S+1E] (respective to the assigned training order), and five sessions per two weeks (5x [1E+1S] or [1S+1E]) during weeks 13-24. The time between training modes was 5-10 min and recovery time between training sessions 48-72 h. The DD-group adhered to the same training program but performed S and E on alternating days, i.e. completing 4 weekly training sessions during the first 12 weeks and 10 sessions per two weeks during the latter 12 weeks. Training sessions were supervised by research staff" (Eklund. 2016).Nutritional intake was controlled through food diaries, which were filled in by the participants for three consecutive days at weeks 0, 12 and 24. Energy intake was analyzed based on the food diaries with a nutrient analysis software (Nutriflow, Flow-team Oy, Finland). The participants received written and verbal nutritional recommendations according to the national guidelines and were asked to maintain constant dietary intake throughout the intervention which included the following strength and endurance training component(s):
- Strength training mainly targeted the knee extensors and flexors as well as hip extensors, with the exercises consisting of horizontal leg press, seated hamstring curls and seated knee extensions. During the initial weeks, the exercises were performed in a circuit (2-4 sets of 15- 20 repetitions with up to 60% of 1RM) and then continued through hypertrophy-inducing training (2-5 x 8-12 at 80-85% of 1RM, 1-2 min rest) towards maximal strength training (2-5 x 3-5 at 85-95% of 1RM, 3-4 min rest). A similar periodization scheme was used for the upper body. Dumbbells and cable pulley machines were used for upper body exercises, and both machines and body weight were utilized for exercises of the trunk. The periodization was repeated during weeks 13-24 with increased training intensity and volume. The duration of each strength session was 50-60 min.
- Endurance training sessions were performed on a cycle ergometer. The training intensities were controlled through heart rate zones, which corresponded to the threshold values of aerobic and anaerobic thresholds. The training consisted of 30-50 min continuous cycling near the aerobic threshold (weeks 1-7 and 13-16), including interval training at and above the anaerobic threshold (weeks 8 and 17 onwards). The interval sessions were initiated and finished with 10-15 minute bouts below the aerobic threshold, with 5-minute altering bouts on the anaerobic threshold and below the aerobic threshold in between.
Interestingly enough, the adherence of those participants who made it to the end of the study was close to 100% in both groups. Against that background it may be only mildly surprising that the adaptational response to the workouts was comparable in all three groups, too.
|Figure 1: Rel. changes in lean mass and body fat over 24 weeks (Eklund. 2016).|
A closer look at the data from the full text does yet reveal the following, at least for some of you, unquestionably significant and important differences:
- Muscle gains - Interestingly enough, the total lower body lean mass didn't increase significantly in the DD (individual days) group; measuring only the trunk lean mass, on the other hand found no increases in the SE-women and ES-men; and no increase in sleeve size was observed in ES-women and SE-men.
- Fat loss - Fat mass decreased in all regions in the DD-groups, while significant changes in ES and SE were not found during the training intervention; furthermore, in women, the difference achieved statistical significance with DD women losing significantly more total body fat than those in the ES and SE groups
Could the lack of effect on fat loss be a mere results of eating too much? Not really. After all, Total energy intake (MJ) at week 0, 12 and 24 in men were as follows 9.3±1.8, 10.2±2.6 and 9.5±2.6 for ES; 9.4±2.0, 9.3±1.7 and 7.9±1.7 for SE; 8.4±2.3, 9.0±1.4 and 9.2±1.6 in DD, respectively. Total energy intake was in women 8±1.2, 7.8±1.8 and 8.2±2.1 for ES; 7.6±1.2, 7.7±1.6 and 7.1±2.1 for SE; 7.0±1.9, 6.9±1.6 and 7.0±1.8 for DD, respectively.
If it's not the diet and the training volume was strictly matched in all groups in the present study, the benefits of training on separate days must have a different reason - a possible explanation Eklund et al. list could be an increase in post-exercise energy costs with more frequent (shorter) training compared to fewer (long) long-duration session (+40% in Almuzaini et al. 1998).References:
- Almuzaini, Khalid S., Jeffrey A. Potteiger, and Samuel B. Green. "Effects of split exercise sessions on excess postexercise oxygen consumption and resting metabolic rate." Canadian Journal of Applied Physiology 23.5 (1998): 433-443.
- Eklund, Daniela, et al. "Fitness, body composition and blood lipids following three concurrent strength and endurance training modes." Applied Physiology, Nutrition, and Metabolism ja (2016).