Abstract available in the Journal of Strength and Conditioning Research

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Context: Strength training induces muscle remodeling and may improve insulin responsiveness. Objective: This study will quantify the impact of resistance training on insulin sensitivity in subjects with the metabolic syndrome and correlate this with activation of intramuscular pathways mediating mitochondrial biogenesis and muscle fiber hypertrophy. Design: Tens ubjects with the metabolic syndrome(MS) and nine sedentary controls underwent 8 wk of supervised resistance exercise training with pre-and post-training anthropometric and muscle biochemical assessments. Setting: Resistance exercise training took place in a sports laboratory on a college campus. Main Outcome Measures: Pre- and posttraining insulin responsiveness was quantified using a euglycemic clamp. Changes in expression of muscle 5-AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) pathways were quantified using immunoblots. Results: Strength and stamina increased in both groups. Insulin sensitivity increased in controls (steady-state glucose infusion rate 7.0 2.0 mg/kg min pretraining training vs. 8.7 3.1 mg/kg min posttraining; P 0.01) but did not improve in MS subjects (3.3 1.3 pre vs. 3.1 1.0 post).Muscleglucosetransporter4increased67%incontrolsand36%intheMSsubjects.Control subjects increased muscle phospho-AMPK (43%), peroxisome proliferator-activated receptor coactivator1 (57%),andATPsynthase(60%),morethanMSsubjects(8,28,and21%,respectively). In contrast, muscle phospho-mTOR increased most in the MS group (57 vs. 32%). Conclusion: Failure of resistance training to improve insulin responsiveness in MS subjects was coincident with diminished phosphorylation of muscle AMPK, but increased phosphorylation of mTOR, suggesting activation of the mTOR pathway could be involved in inhibition of exercise training-related increases in AMPK and its activation and downstream events

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Objectives: The purpose of the study was to identify the level of accuracy in velocity measurement from a newly developed inertia sensor.Design and Methods: Five subjects performed two dumbbell exercises for total of four sets of ten repetitions with a light intensity. Velocity data were taken and considered for analysis from two devices; the inertia sensor, wirelessly connected via Bluetooth™ to a smartphone, and a motion capture system. Both data were taken at the sampling frequency of 200 Hz. Identical data sets of peak and average velocity were analyzed with Pearson product-moment zero-order correlation using total 200 data points (5 subjects, 4 sets, and 10 repetitions) on both exercises with p value of 0.05. Data were also analyzed using the same statistical procedure for left and right side to ensure the device-device data consistency. Results: Results showed high correlations in both exercises between the two velocity measurement methods (0.80 - 0.92), indicating the accuracy of the data from the inertia sensor is supportive. Left and right side correlations were also high from the inertia sensor (0.90 - 0.93) indicating that the data were similar with relatively identical movements between the two limbs.Conclusions: With the accuracy of the velocity measurement, this would potentially replace currently used, wired devices to accommodate user-friendly, accessible to more exercises to measure velocity. (Journal of Trainology 2015;4:15-18)

Objectives: The purpose of this investigation was to determine what effect a bilateral strength training regimen has on isometric force production symmetry and if changes in force production symmetry can be accounted for by differences in pre-intervention strength levels. Design: Sixteen recreationally trained males (1-RM squat: 146.8 ± 23.0 kg.) were assigned to two groups for the 7-week training intervention: strong (S) and weak (W) based on pre-training squat isometric peak force allometrically scaled (IPFa) at 120° knee angle. Methods: Subjects completed a 7-week training intervention following a block-periodized model and were tested on measures of dynamic (1RM squat) and isometric (isometric squat at 90° and 120° knee angle) strength pre- and post-intervention. The degree of bilateral lower limb asymmetry was calculated as a percentage where 0% symmetry index (SI) indicates perfect symmetry on the isometric squat.Results: ANCOVA results showed no statistical difference between groups for all dependent variables when pre-intervention IPFa 120° scores were used as the covariate. Paired t-tests results showed both groups statistically improved 1RM squat and IPFa 120° (p < 0.05). IPFa 120° SI decreased statistically from pre-training in the W group (p = 0.03). Independent t-test results showed the W group had statistically larger pre-intervention SI scores for IPFa 90° (p = 0.045) and IPFa 120° (p = 0.007); however this difference was no longer present following strength training. There was a strong inverse relationship between pooled IPFa 120° and IPFa 120° SI (r = -0.64, p = 0.004). Conclusions: The findings of the current study support the notion that weaker individuals can augment lower limb symmetry with strength training. The same does not seem to be true for stronger individuals who already have a low symmetry index score. These findings indicate that strength training improves force production symmetry in relatively weak males, which may be important for bilateral tasks and injury potential reduction.

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