The Ergogenic Effects Of Carbohydrate Supplementation On Force Output And Slope Of Fatigue During A Selected Resistance Protocol.
Journal of Strength & Conditioning Research. 24 Supplement 1:1, January 2010.
Wax, Ben; Kinzey, Steve; Lyons, Brian; Brown, Stan
The ergogenic effects of carbohydrate ingestion prior to and during resistance training has yielded mixed results over the years. A number of investigations have attempted to determine the ergogenic effects of carbohydrate supplementations utilizing squats or some type of circuit style of resistance training. Past These investigations measured performance in terms of a specific number of repetitions successfully performed, which failed to account for central fatigue factors related to the specific exercise chosen. Few investigations have measured the relationship between carbohydrate supplementation ingestion and force output during periods of voluntary and stimulated contractions. To determine the ergogenic effects of carbohydrate ingestion supplementation on force output during a selected resistance protocol. 6 male subjects with a minimum of 3 years of bodybuilding and/or power lifting backgrounds training performed one mock trial and two randomly assigned exercise trials one week apart, in which the experimental treatment, glucose polymer (GP) and placebo (P), were randomly assigned and administered in a double blind fashion. The subjects were seated with the knee at an angle slightly less than 900 by a horizontal strap securely anchored just above the malleoli and attached at the other end to the a strain gauge. Subjects were strapped at the waist to maintain muscle length and prevent substantial use of hip extensors. The subjects ingested either a 10% GP solution (0.1g[middle dot]kg-1[middle dot]body mass-1) or P 5 minutes before performing a maximal voluntary contraction with their perceived dominant leg to determine force output. Following another 5 minute rest and thereafter at 6 minute intervals a GP (0.17g[middle dot]kg-1[middle dot]body mass-1) or P solution was ingested during the protocol. The protocol consisted of one leg isometric contractions at 50% of their previously determined one repetition maximum for 20 seconds, followed by 40 seconds of rest between contractions, until failure occurred. Failure was defined as the inability to sustain target force for 5 consecutive seconds. The decrease in force generating capacity was tested from brief maximal voluntary contractions (MVC's) and short bursts of 60 Hz stimulation applied at 5 minute intervals. Force was measured using a Transducer Techniques 300 pound strain gauge type load cell, which sent a signal to an amplifier through a fixed wire. Once the signal was amplified it was transferred to a desktop computer for interpretation. Sampling was recorded at 1000 Hz. A paired sample T-test revealed performance measured in time to exhaustion (29 +/- 13.08 minutes for GP and 16 +/- 8.12 for P), total force production (492.92 +/- 192.42 kilograms for GP and 306.62 +/- 130.07 kilograms for P), and slope of fatigue (-.0594 +/- -.0299 for GP and -.0300 +/- -.0109 for P) were significantly different in the GP than Pbetween treatments (p < .05).
The results suggest GP ingestion prior to and during selected resistance protocols increase time to exhaustion, total force production and slope of fatigue in well trained lifters. In conclusion, the ingestion of a liquid carbohydrate supplement prior to and intermittently during selected resistance protocols appears to provide an ergogenic effect that is reflected by increased force production and delayed time to fatigue.
