Scott R. Richmond

The effects of varied rest periods between sets to failure using the bench press in recreationally trained men.

The purpose of this study was to determine the rate of recovery for recreational weight trainers between 2 sets of bench press to volitional exhaustion. Twenty-eight men performed 2 sets of the bench press at 75% of their previously determined 1 repetition maximum (1RM) to volitional exhaustion. Rest periods of 1, 3, or 5 minutes between sets were utilized on the 3 separate testing days. There was a significant decrease in the number of repetitions performed between the second sets at all rest periods. There were no significant differences in work performed (repetitions × weight) during the second set with the 3- and 5-minute rest periods, but the total work with a 1-minute rest period (1,389.1 ± 529.9) was significantly less than both the 3- (1,494.9 ± 451.0) and 5-minute (1,711.4 ± 478.0) rest period. The data indicated that subjects were unable to fully recover between the first and second sets of maximal resistance exercise, regardless of the rest period. However, subjects were able to maintain a performance level of 8–12 repetitions and sustain the total work performed per set with as little as 3 minutes rest between sets.

Insulin-like growth factor I-mediated skeletal muscle hypertrophy is characterized by increased mTOR-p70S6K signaling without increased Akt phosphorylation

Background Insulin-like growth factor I (IGF-I) is an anabolic hormone that is known to induce skeletal muscle hypertrophy. However, the signaling pathways mediating IGF-Is hypertrophic effect in vivo are unknown. Method The phosphorylation of 46 proteins was investigated by Kinetworks proteomic analysis in the gastrocnemius muscle of transgenic mice overexpressing IGF-I myosin light chain/muscle specific IGF-I (MLC/mIgf-I) and wild-type littermates. Results In the hypertrophic muscle of MLC/mIgf-I mice, we observed increased phosphorylation of phosphoinositide-dependent protein kinase 1 (PDK1; 53% increase), the mammalian target of rapamycin (mTOR; 112% increase), and p70 S6 kinase (p70S6K) (254% increase) but no significant change in Akt phosphorylation (4% decrease). Furthermore, we found reduced phosphorylation of MAP kinase kinase 1 and 2 (MEK1/2) (60% decrease) and of mitogen-activated protein kinase kinases 3 and 6 (MKK3/6) (50% decrease) in muscle from transgenic mice, suggesting that the hypertrophic and mitogenic effects of IGF-I are mediated via distinct signaling pathways in skeletal muscle and that inhibition of the mitogen-activated protein (MAP) kinase pathway may be required for the IGF-I-induced hypertrophic effect. Single-fiber analysis revealed a trend toward a higher percentage of the fast twitch fibers (IIb and IIx) in the transgenic mice. Conclusion Persistent overexpression of IGF-I in mice skeletal muscle results in hypertrophy, which is likely mediated via the mTOR/p70S6K pathway, potentially via an Akt-independent signaling pathway.

Postprandial metabolism in resistance-trained versus sedentary males

INTRODUCTION This investigation examined if postprandial metabolism differed between resistance-trained [(RT), N = 12] and sedentary [(SED), N = 12] males. A secondary objective was to determine whether different resistance-training programs [bodybuilding (BB), N = 8 and power/weight-lifting (PL), N = 8] resulted in disparate effects on postprandial energy metabolism. METHODS Moderate fat [(MF), 37% carbohydrate, 18% protein, and 45% fat] and high carbohydrate [(HC), 79% carbohydrate, 20% protein, and 1% fat] meals were randomly administered, and postprandial metabolism was measured for 240 min. Carbohydrate oxidation, fat oxidation, diet-induced thermogenesis (DIT), and glucose and insulin areas under the curve (AUC) were calculated. RESULTS Fat oxidization/lean body mass (LBM) was significantly greater in SED after the HC (RT, 0.27 +/- 0.02 g vs SED, 0.33 +/- 0.02 g, P = 0.017) and MF (RT, 0.34 +/- 0.02 g vs SED, 0.39 +/- 0.02 g, P = 0.036) meals. Carbohydrate oxidation/LBM was significantly greater in RT after the HC meal (RT, 0.87 +/- 0.03 g vs SED, 0.74 +/- 0.04 g, P = 0.017) only. DIT and DIT/LBM were significantly greater in RT compared with SED after the HC meal (DIT: RT, 351 +/- 21 kJ vs SED, 231 +/- 23 kJ, P = 0.001; DIT/LBM: RT, 5.25 +/- 0.028 kJ vs SED, 3.92 +/- 0.37 kJ, P = 0.009). The AUC for both glucose and insulin were significantly greater in SED compared with RT in response to the HC meal but not the MF meal. There were no differences in the BB and PL groups for any measured variables in response to either the HC or MF meals. CONCLUSION These data indicate that postprandial metabolism is different between resistance-trained and sedentary males but that no such differences exist with different resistance training styles.

Forskolin attenuates the action of insulin on the Akt-mTOR pathway in human skeletal muscle

Forskolin (FSK) is capable of both stimulating and inhibiting the intracellular signaling pathways of protein synthesis tissues other than skeletal muscle. The purpose of this investigation was to determine if FSK administration affects various elements of the protein kinase B (Akt)-mammalian target of rapamycin (mTOR) pathway in human skeletal muscle. Ten (n = 10) healthy, young (21.6 +/- 1.3 years), nonobese (body mass index = 25.5 +/- 3.5 kg.m-2), recreationally active males were selected for participation. Following an 8 h fast, 2 muscle biopsies of the vastus lateralis were performed. The samples were sectioned and exposed to 4 in vitro treatment conditions: basal, FSK, insulin (INS), and FSK+INS. The samples were then analyzed for total and phosphorylated levels of Akt, mTOR, S6 kinase (S6K1), and 4E binding protein (4EBP1). Akt phosphorylation was significantly greater in the INS-treated samples compared with the basal and FSK conditions (p = 0.007). Furthermore, the ratio of phosphorylated Akt to total Akt (P/T) was higher in the INS samples compared with the basal and FSK samples (p = 0.001). There were no differences in mTOR phosphorylation among the 4 groups; however, total mTOR was significantly greater in the FSK+INS group (p = 0.006). There were also no differences in phosphorylated or total levels of S6K1 among the 4 groups. However, 4EBP1 phosphorylation was significantly greater in the INS-treated samples compared with the basal (p = 0.003) and FSK (p = 0.004) treatments. There were no differences in the ratio of phosphorylated 4EBP1 to total 4EBP1 (P/T) among the 4 groups. These results indicate that FSK does not activate the Akt-mTOR pathway in human skeletal muscle; however, these results suggest that FSK may inhibit the actions of INS on this pathway.

Determining the Impact of Anthropometric Factors on Rock Climbing Performance: 3377 Board #282 June 2 3

The purpose of this study was to determine whether anthropometric factors have an effect on overall performance in rock climbing between three different difficulties of rock walls. Fourteen, recreational rock climbers participated in this study (Age21.93+/-2.62y, Height176.8+/-11.1cm, Weight73.4+/-18.7kgs, % Fat21.02 +/6.41, BMI23.36+/4.59). The anthropometric tests included: push-ups, sit-ups, pull-ups, vertical jump, and sit and reach. Immediately following these tests, the participants climbed the three different rock walls for approximately 10 minutes. The data collected is represented through the average number of climbs, distance traveled, and an RPE scale, to determine overall performance. A stepwise regression test showed some anthropometric variables were significant predictor on climbing success. However, the specific anthropometric variables differed based on the level of difficulty of the wall.