Fernando Gripp

Influence of the knee flexion on muscle activation and transmissibility during whole body vibration.

The influence of the knee flexion on muscle activation and transmissibility during whole body vibration is controversially discussed in the literature. In this study, 34 individuals had electromyography activity (EMG) of the vastus lateralis and the acceleration assessed while squatting with 60° and 90° of knee flexion either with or without whole-body vibration (WBV). The conditions were maintained for 10s with 1min of rest between each condition. The main findings were (1) the larger the angle of knee flexion (90° vs. 60°), the greater the EMG (p<0.001), with no difference on acceleration transmissibility; (2) for both angles of knee flexion, the addition of WBV produced no significant difference in EMG and higher acceleration compared to without WBV (p<0.001). These results suggest that the larger the knee flexion angle (60° vs. 90°), the greater the muscle activation without acceleration modification. However, the addition of WBV increases the transmissibility of acceleration in the lower limbs without modification in EMG of vastus lateralis.

The effects of passive warm-up vs. whole-body vibration on high-intensity performance during sprint cycle exercise.

Abstract Avelar, NCP, Costa, SJ, da Fonseca, SF, Tossige-Gomes, R, Gripp, FJ, Coimbra, CC, and Lacerda, ACR. The effects of passive warm-up vs. whole-body vibration on high-intensity performance during sprint cycle exercise. J Strength Cond Res 26(11): 2997–3003, 2012—The purpose of this study was to compare the effects of passive warm-up (PW), whole-body vibration (WBV), and control (C) on high-intensity performance during sprint cycle exercise. Six recreationally trained men performed a 30-second sprint cycle test after the 3 aforementioned conditions; each test was carried out on a different day after balanced-order experimental tests. The WBV consisted of 5 minutes of squats associated with WBV (45 Hz, 2 mm). The PW consisted of 30 minutes of PW using a thermal blanket on the thighs and legs (35 W). The C consisted of 30 minutes of no warm-up with the subject lying down. Motor neuron excitability from the vastus lateralis muscle, evaluated by electromyography (EMG), was determined before exercise at rest and during sprint cycle exercise. Blood lactate levels (BLs), evaluated by spectroscopy, and muscle temperature (MT) of the thigh, estimated indirectly by measuring skin temperature, were determined at following time points: before exercise at rest (before and after experimental conditions), immediately, and 3 minutes after the 30-second sprint cycle test. Peak power, relative power, relative work, time of peak power, and pedaling cadence were significantly higher in the WBV compared with that for C (p < 0.05). Although MT was significantly greater in PW compared with that in WBV and C before exercise (p < 0.01), no significant differences were observed between the experimental conditions for BL immediately after sprint cycle exercise (p = 0.35) and in EMG during sprint cycle exercise (p = 0.16). Thus, it is plausible to suggest WBV as a method for an acute increase in high-intensity performance during sprint cycle exercise for athletes immediately before competition or training.

Carbohydrate Ingestion During Exercise Does Not Delay the Onset of Fatigue During Submaximal Cycle Exercise

Lacerda, ACR, Alecrim, P, Damasceno, WC, Gripp, F, Pinto, KMC, and Silami-Garcia, E. Carbohydrate ingestion during exercise does not delay the onset of fatigue during submaximal cycle exercise. J Strength Cond Res 23(4): 1276-1281, 2009-The objective of this study was to evaluate the effect of the ingestion of carbohydrate (CHO, in the form of maltodextrin) or placebo (PLAC, in the form of gelatin) on the physical performance of cyclists during submaximal exercise until fatigue on an ergometric cycle. Nine volunteers exercised on 2 separate occasions at least 2 days apart. On each occasion, after 48 hours of a balanced diet, they pedaled at approximately 66% &OV0312;o2peak until fatigue. Every 15 minutes, 150 mL of water and 18 capsules, containing either 0.5 g of CHO or PLAC (∼0.13 g·kg−1 of body weight), were ingested in accordance with a double-blind, randomized protocol. The results show that after 40% of total exercise time, blood glucose levels in the CHO test returned to baseline levels. However, in the PLAC trial these levels failed to return to baseline levels, remaining lower than levels recorded in the CHO test after 60% of total exercise time. Despite these results, CHO ingestion failed to delay the onset of fatigue (CHO: 91.8 ± 10.1 minutes vs. PLAC: 93.3 ± 16.1 minutes; p = 0.87). In practical terms, coaches and trainers should consider that CHO ingestion in previously fed users does not delay the onset of fatigue during submaximal cycle exercise.