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, Antonio1,2; Hita-Contreras,
Fidel1,2; 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.
