Resistance Training

This study examined the effect of repetitions per set as a function of changing load (percentage of one-repetition maximum) on the accuracy of intraset repetitions in reserve (RIR) predictions in the back squat and bench press. Twelve resistance trained men completed three multi-set back squat and bench press training sessions that differed in the number of target repetitions (session 1: 10 repetitions; session 2: 8 repetitions; session 3: 6 repetitions). The last set of each session was performed until muscular failure in which subjects verbally indicated when they perceived 4 RIR and 1 RIR. For each RIR prediction, RIRDIFF [perceived RIR - actual RIR] was calculated.
Differences in RIRDIFF were analyzed using both raw RIRDIFF (including positive and negative values) and absolute RIRDIFF (absolute values) via MANOVA and factorial ANOVA. The model controlled for the covariates session-type, percentage of 1RM, and total repetitions per set. Overall, RIR accuracy at the predicted 1 RIR was significantly greater (i.e., lower absolute RIRDIFF) than at the predicted 4 RIR in both the bench press (4 RIR: 1.00 ± 0.18 vs. 1 RIR: 0.69 ± 0.12; p = 0.028) and the squat (4 RIR: 1.43 ± 0.31 vs. 1 RIR: 0.79 ± 0.26; p = 0.007). No covariates significantly affected RIR accuracy (p = 0.085 – 0.518) at the predicted 1 RIR. However, at the predicted 4 RIR, the covariate repetitions per set affected raw RIRDIFF in both the squat (p = 0.007) and bench press (p < 0.001), indicating that subjects tended to overpredict RIR in lower repetition sets and underpredict RIR in higher repetition sets.

This study examined whether accuracy of intraset RIR predictions changes over time. Nine resistance trained men completed three bench press training sessions per week for six weeks, with the last set of each session performed until muscular failure. During the set to failure, subjects verbally indicated when they perceived 4 repetitions in reserve (RIR) and 1 RIR during the set. For each RIR prediction, the difference between perceived RIR and actual RIR was calculated as RIRDIFF. We analyzed differences in RIRDIFF using both the raw RIRDIFF (including positive and negative values) and the absolute values of all RIRDIFF using a factorial MANOVA. Covariates included proximity to failure of the RIR prediction, total repetitions performed per set, percentage of one-repetition maximum lifted, the week of training, and the session (1, 2, or 3 within each seek). For the raw RIRDIFF all covariates, except for percentage of 1RM (p > 0.05) were significantly related to the outcome measure at both the predicted 4 and 1 RIR (p < 0.001 to p = 0.04). Specifically, RIRDIFF was significantly higher in weeks 1-4 versus weeks 5-6 (p < 0.001 to p = 0.005). However, the only covariate which significantly impacted the absolute value RIRDIFF at both the predicted 4 (p = 0.033) and 1 RIR (p = 0.022) was total repetitions per set. These results indicate that trained men tend to shift from overpredicting to underpredicting RIR over time and that more repetitions in a set is related to more inaccurate RIR predictions. However, the actual accuracy (i.e., absolute value RIRDIFF) did not significantly change over six weeks of training.

This study examined the acute and chronic responses of brain-derived neurotrophic factor (BDNF), cathepsin B (CatB), insulin-like growth factor-1 (IGF-1), and interleukin-6 (IL-6) and if changes in these biomarkers were correlated during resistance training. Fourteen resistance trained men performed resistance training 3 days per week for 6 weeks in two groups. The only difference between groups was the proximity to failure of each set (4-6 repetitions in reserve or 1-3 repetitions in reserve). Serum was collected immediately before and after training on day 1 of weeks 1 and 6.
There were no significant group interactions for any of the biomarkers assessed, there were no main effects for time (p>0.05), and no significant correlations were observed between any of the biomarkers. However, a significant main effect for exercise for BDNF (p=0.03) and IL-6 (p=0.003) was observed. For CatB, a significant exercise × time (p=0.002) interaction was observed, indicating differences in the acute change of CatB in week 6 (+15.78%; g=0.25) vs. week 1 (-7.46%; g=0.13). In summary, these results suggest that multi-joint resistance exercise far from failure can confer a BDNF response. This investigation is the first to demonstrate the potential for acute resistance exercise to elicit a transient increase in CatB.

This study examined the longitudinal relationship between repetitions in reserve (RIR) and average concentric velocity (ACV) in the back squat and bench press exercises. Fourteen resistance-trained men were randomized into two groups (4-6RIR or 1-3RIR) and completed a six-week program. The RIR/ACV slope was significantly greater (p<0.001) in the bench press (0.027±}0.001m.s-1) than squat (0.020±}0.001m.s-1), and was steeper in 1-3RIR than 4-6RIR (p<0.001). The RIR/ACV relationship varied from set-to-set (p=0.001); however, the largest difference in ACV at the same RIR from set-to-set was only 0.044 m.s-1; likely not practically meaningful. The RIR/ACV relationship changed over time (p=0.004); however, since training was not to failure, it is unclear if this longitudinal change was due to improved RIR accuracy or a true change in the RIR/ACV relationship. Therefore, the RIR/ACV relationship is exercise-specific and practically stable from set-to-set; however, future research is needed to determine the long-term stability of this relationship.

This study examined the effect of resistance training proximity to failure on strength, muscle hypertrophy, and fatigue. Fourteen men were randomized into two groups (4-6 rating of perceived exertion-RPE per set or 7-9 RPE per set) and completed an eight-week program. Squat and bench press strength, muscle thickness, subjective fatigue, muscle soreness, and biomarkers (creatine kinase-CK and lactate dehydrogenase-LDH) were assessed. There were no significant differences (p>0.05) in the rate of strength gains and equivalence testing revealed hypertrophy was not statistically similar nor different. All results for indirect markers of muscle damage and fatigue indicated similar recovery between groups within 48 hours; however, a small between group effect size (g=0.39) existed indicating higher session RPE in the 7-9 RPE group across the entire training program. These results suggest that strength and possibly hypertrophy outcomes are similar when training each set to 4-6 RPE or 7-9 RPE in trained men.

This study examined the relationship between average concentric velocity (ACV) and repetitions in reserve (RIR) in the back squat, bench press, and deadlift. Fourteen resistance-trained men performed three experimental sessions (one for each exercise), which was comprised of 4 sets to failure at 80% of one-repetition maximum. The ACV was recorded on every repetition of every set and cross-referenced with RIR. The main findings of this study were that RIR was a significant predictor of ACV for all three exercises; the mean set ACV was significantly different between exercises (p<0.001); and the relationship between RIR and ACV was set-dependent (p<0.001). However, the within-exercise difference in ACV from set-to-set is unlikely to be practically significant as all of these ACV differences were below the threshold of 0.06 m.s-1, which is the smallest worthwhile change in ACV. Therefore, these results suggest that the RIR/ACV relationship is exercise-specific, and is stable from set-to-set.

This study examined if multi-joint resistance exercises could elicit expression of biomarkers associated with neuroprotection. Thirteen well-trained males performed 4 sets to failure at 80% of a one-repetition maximum (1RM) on the back squat, bench press, and deadlift. The biomarkers measured immediately pre- and post-exercise were brain derived neurotrophic factor (BDNF), insulin-like growth factor 1 (IGF-1), cathepsin B (CatB), and interleukin 6 (IL-6). There was a main time effect (p<0.01) for BDNF with significant increases in the deadlift (p=0.01) and bench press (p=0.01) conditions, but not the squat (p=0.21). There was a main time effect (p<0.01) for IL-6 with a significant increase in the squat (p<0.01). There was no significant increase in CatB or IGF-1 (p>0.05). Additionally, there was no significant relationship between BDNF and IL-6 response.