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The Effects of Instant Coffee on the Myotatic Reflex During Bench Pressing: A Gender Comparison
Author(s) -
Ruffner Kayla,
DiFiore Brittany,
Smith Bridget,
Trivisonno Abigail,
Slack Grant,
Cooper Cyrena,
Lowery Lonnie
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.317.4
Subject(s) - bench press , crossover study , reflex , medicine , repeated measures design , analysis of variance , physical therapy , psychology , resistance training , placebo , mathematics , anesthesia , statistics , alternative medicine , pathology
Coffee is widely consumed by exercising men and women throughout the world. Previous work from our laboratory suggests coffee enhances the stretch reflex during bench pressing. In partial contrast, Carins and colleagues (2003) were able to enhance the stretch reflex in men but not women during a non‐exercise intervention using glutamate. Whether coffee differently affects reflexes in each gender during explosive exercise remains unclear. The purpose of this study was to compare the neuromuscular reflexes of the upper body between sexes after consuming two test beverages. We hypothesized that men would have a greater enhancement of reflexive bench press performance compared to women after ingesting Via Instant Coffee (VIA) compared to decaffeinated coffee (DCF). In a blinded, crossover experimental design, 34 resistance trained individuals were tested at 50% of their one repetition maximum (1RM) on the Smith Bench Press one hour after ingesting 525 mL VIA or DCF. Force (FOR) and time to peak power (TtPP) were measured using the Smith machine and Ballistic Measurement System (BMS, Innervations Inc, South Australia). After repeated measures ANOVA and Newman‐Keuls post hoc testing, absolute bench press FOR was enhanced by prior stretch in the DCF condition (mean ± SD) in men (806.7 ± 206.3 N vs. 1040.5 ± 287.3 N; p≤0.05) and women (318.6 ± 65.2 N vs. 406.9 ± 113.4 N; p≤0.05) with larger enhancement after consuming VIA (men 806.0 ± 222.9 N vs. 1114.1 ± 343.8 N; p≤0.05 and women (327.0 ± 67.1 N vs. 403.9 ± 89.5 N; p≤0.05). Statistical correction for body mass, however, abolished sex differences (p≥0.05). TtPP enhancement from prior stretch tended to differ in the DCF condition in men (328 ± 70 ms vs. 216 ± 80 ms) and in women (378 ± 90 ms vs. 318 ± 110 ms; interaction p=0.096). This trend reached statistical significance after consuming VIA in men (315 ± 70 ms vs. 194 ± 80 ms; p≤0.05) and in women (367 ± 100 ms vs. 302 ± 100 ms; p≤0.05). We conclude that the stretch reflex enhances explosive bench press performance in both sexes with men gaining greater absolute gains than women, particularly after coffee consumption. Future studies that compare sexes in the bench press are cautioned to adjust force measures for body mass differences.