Department of Exercise Science and Health Promotion

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.

One modality to improve quality of life, in Breast Cancer Survivors (BCS), is physical activity (PA). Less than 30% of BCS participate in PA. The purpose of this study is to explore BCS’s intention to exercise. Seventy-five BCS patients, undergoing treatment, completed a survey. The survey assessed the following: Health care practitioner influence, Demographics, Stages of Change (SOC), anxiety and depression, perceived barriers to exercise, past and current exercise, and the constructs of the Theory of Planned Behavior (TPB). BCS who were older, had less education, did not exercise before diagnosis, were in the pre-contemplation and contemplation stages, and/or exhibited a low Perceived Behavioral Control had a lower intention to exercise. Incorporating the findings from this research into an intervention may assist with increasing intention to exercise among BCS.

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 the accuracy of predicting back squat and bench press one repetition maximum (1RM) from submaximal average concentric velocity (ACV).Seventeen resistance trained men performed a warm-up and 1RM test on the squat and bench press, in which ACV was assessed on all repetitions. The ACVs during the warmup closest to 1.0 and 0.5 m.s-1 were used in a 2-point linear regression forecast of 1RM and the ACVs established at the loads closest to 20, 50, 70, and 80% of 1RM were used in a 4-point 1RM prediction. An ANOVA indicated significant differences between predicted and actual 1RM for all predictions (p<0.001). Both Bland-Altman and Mountain plots confirmed the findings of the ANOVA as data were not tightly conformed to the respective zero difference lines. Therefore, these results suggest that a linear regression forecast using submaximal ACV does not accurately predict 1RM in the ¬back squat and bench press.

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.

The purpose of this research was to investigate the effects of eccentric phase
duration on concentric outcomes at 60% and 80% of one-repetition maximum (1RM) in
the squat and bench press. Sixteen resistance-trained males completed four laboratory
visits as follows: Day 1- 1RM testing; Day 2- establishment of normative eccentric
durations; Days 3 and 4- randomized fast (0.75 times) or slow (2 times) eccentric
duration variations, which were controlled by visual and auditory metronomes. Eccentric
duration was significantly and inversely correlated with average concentric velocity
(ACV) at 60% (r = 0.408) and 80% (r = -0.477) of 1RM squat and at 100% of 1RM
bench press. At 60% of 1RM squat, both fast and slow eccentric conditions produced
greater (p<0.001) peak concentric velocity (PCV) than normative duration with fast also
producing greater PCV than slow (p=0.044). Therefore, fast eccentric durations may
benefit concentric velocity.

This research investigated the relationship between exercise training and
cathepsin B expression in the 3xTg-AD murine model of Alzheimer’s disease. 3xTg-AD
mice were assigned to control (Tg, n=10), aerobic training (Tg+AT, n=10), or resistance
training (Tg+RT, n=10). RotaRod peak latency and grip strength were assessed as preand
post-measurements. Skeletal muscle was collected after training and analyzed for
cathepsin B protein. Tg+RT showed greater grip strength than Tg and Tg+AT at posttesting
(p ≤ 0.05). Only Tg+AT showed an improvement in RotaRod peak latency (p ≤
0.05). Gastrocnemius weight was greater in Tg+RT compared to Tg (p ≤ 0.05), and no
differences were observed in cathepsin B or procathepsin B expression (p > 0.05). This
data suggests that cathepsin B was not induced by either mode of exercise training,
however, physical function and muscle mass were improved, therefore inclusion of both
training modalities may address peripheral comorbidities in Alzheimer’s disease.

The primary purpose of this study was to investigate the effects of aerobic and
resistance training on BDNF and IGF-I expression in a 3xTg-AD mouse model of
Alzheimer’s disease. Twenty-four 3xTg-AD mice were randomly assigned to either an
aerobic (AT, n=8), resistance (RT, n=8), or control (CNT, n=8) group. Intervention
groups underwent 9 weeks of exercise training. Motor behavior and grip strength were
measured pre- and post- intervention. Our results showed a significant increase in
hippocampal BDNF expression in AT mice after a 9-week intervention. Further, AT mice
were found to have higher concentrations of IGF-I, and improved motor behavior when
compared to RT and CNT. No significant differences were observed in IGF-I
concentration between RT and other groups. RT improved grip strength after nine weeks
of training. These findings support the use of AT and RT as a tool to improve
comorbidities found in Alzheimer’s disease.