Three JSCR interesting abstracts!

Effects of a Short-Term Carbohydrate-Restricted Diet on Strength and Power Performance

Sawyer, Jason C.¹; Wood, Richard J.²; Davidson, Patrick W.²; Collins, Sean M.³; Matthews, Tracey D.²; Gregory, Sara M.²; Paolone, Vincent J.²

Abstract: Sawyer, JC, Wood, RJ, Davidson, PW, Collins, SM, Matthews, TD, Gregory, SM, and Paolone, VJ. Effects of a short-term carbohydrate-restricted diet on strength and power performance. J Strength Cond Res 27(8): 2255–2262, 2013—The purpose of the study was to examine the effects of switching from a habitual diet to a carbohydrate-restricted diet (CRD) on strength and power performance in trained men (n = 16) and women (n = 15). Subjects performed handgrip dynamometry, vertical jump, 1RM bench press and back squat, maximum-repetition bench press, and a 30-second Wingate anaerobic cycling test after consuming a habitual diet (40.7% carbohydrate, 22.2% protein, and 34.4% fat) for 7 days and again after following a CRD (5.4% carbohydrate, 35.1% protein, and 53.6% fat) for 7 days. Before both testing sessions, body weight and composition were examined using bioelectrical impedance analysis. Three 2 × 2 multiple analyses of variance were used to compare performance variables between the habitual diet and CRD. Subjects consumed significantly fewer (p < 0.05) total kilocalories during the CRD (2,156.55 ± 126.7) compared with the habitual diet (2,537.43 ± 99.5). Body mass decreased significantly (p < 0.05). Despite a reduction in body mass, strength and power outputs were maintained for men and women during the CRD. These findings may have implications for sports that use weight classes, and in which strength and power are determinants of success. A CRD may be an alternative method for short-term weight loss without compromising strength and power outputs. The use of a 7-day CRD could replace weight loss methods employing severe dehydration before competition.

Effects of 12-Week Proprioception Training Program on Postural Stability, Gait, and Balance in Older Adults: A Controlled Clinical Trial

Martínez-Amat, Antonio^1,2; Hita-Contreras, Fidel^1,2; Lomas-Vega, Rafael¹; Caballero-Martínez, Isabel¹; Alvarez, Pablo J.²; Martínez-López, Emilio³

Abstract: Martínez-Amat, A, Hita-Contreras, F, Lomas-Vega, R, Caballero-Martínez, I, Alvarez, PJ, and Martínez-López, E. Effects of 12-week proprioception training program on postural stability, gait, and balance in older adults: a controlled clinical trial. J Strength Cond Res 27(8): 2180–2188, 2013—The purpose of this study was to evaluate the effect of a 12-week–specific proprioceptive training program on postural stability, gait, balance, and fall prevention in adults older than 65 years. The present study was a controlled clinical trial. Forty-four community dwelling elderly subjects (61–90 years; mean age, 78.07 ± 5.7 years) divided into experimental (n = 20) and control (n = 24) groups. The participants performed the Berg balance test before and after the training program, and we assessed participants' gait, balance, and the risk of falling, using the Tinetti scale. Medial–lateral plane and anterior–posterior plane displacements of the center of pressure, Sway area, length and speed, and the Romberg quotient about surface, speed, and distance were calculated in static posturography analysis (EPS pressure platform) under 2 conditions: eyes open and eyes closed. After a first clinical evaluation, patients were submitted to 12 weeks proprioception training program, 2 sessions of 50 minutes every week. This program includes 6 exercises with the BOSU and Swiss ball as unstable training tools that were designed to program proprioceptive training. The training program improved postural balance of older adults in mediolateral plane with eyes open (p < 0.05) and anterior–posterior plane with eyes closed (p< 0.01). Significant improvements were observed in Romberg quotient about surface (p < 0.05) and speed (p < 0.01) but not about distance (p > 0.05). After proprioception training, gait (Tinetti), and balance (Berg) test scores improved 14.66% and 11.47% respectively. These results show that 12 weeks proprioception training program in older adults is effective in postural stability, static, and dynamic balance and could lead to an improvement in gait and balance capacity, and to a decrease in the risk of falling in adults aged 65 years and older.

Experience in Resistance Training Does Not Prevent Reduction in Muscle Strength Evoked by Passive Static Stretching

Serra, Andrey J.¹; Silva, José A. Jr¹; Marcolongo, Alessandra A.²; Manchini, Martha T.¹; Oliveira, João V.A.²; Santos, Luis F.N.²; Rica, Roberta L.²; Bocalini, Danilo S.¹

Abstract: Serra, AJ, Silva Jr, JA, Marcolongo, AA, Manchini, MT, Oliveira, JVA, Santos, LFN, Rica, RL, and Bocalini, DS. Experience in resistance training does not prevent reduction in muscle strength evoked by passive static stretching. J Strength Cond Res 27(8): 2304–2308, 2013—This study examined whether passive static stretching reduces the maximum muscle strength achieved by different body segments in untrained and resistance-trained subjects. Twenty adult men were assigned to 1 of the following groups: untrained (UT, N = 9) and resistance-trained (RT, N = 11) groups. The subjects performed six 1 repetition maximum (1RM) load tests of the following exercises: horizontal bench press, lat pull-downs, bicep curls, and 45° leg press. The results achieved in the last two 1RM tests were used for statistical analyses. A passive static stretching program was incorporated before the sixth 1RM test. The body fat content was significantly higher in the UT group compared with the RT group (p < 0.0001). Moreover, the RT group showed significantly higher proportion of lean body mass compared with the UT group (p < 0.0001). Maximum muscle strength on all 4 exercises was significantly reduced in both groups after stretching (p < 0.01). Furthermore, the magnitude of muscle strength reduction was similar for the UT and the RT groups. The exception was for barbell curls, in which the muscle strength depression was significantly higher in the UT group compared with the RT group (p < 0.0001). In conclusion, the passive static stretching program was detrimental to upper- and lower-body maximal muscle strength performance in several body segments. The negative effects of stretching were similar for subjects participating in resistance training regimens.