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CAFFEINE ABSTINENCE IN HABITUATED USERS: CARDIOVASCULAR AND PERCEPTUAL RESPONSES TO EXERCISE WITH BLOOD FLOW RESTRICTION

Abstract

Chance J. Davidson, Matthew A. Chatlaong, Daphney M. Stanford, William M. Miller, Matthew B. Jessee. University of Mississippi, University, MS.

BACKGROUND: Since caffeine affects blood pressure (BP), studies using blood flow restriction resistance exercise (BFR-RE) commonly require caffeine abstinence. For habitual users, effects may be attenuated, and it is unknown if abstinence alters responses to BFR-RE. PURPOSE: Compare cardiovascular and perceptual responses to BFR-RE when habitual users consume or abstain from caffeine. METHODS: 11 participants completed a 3 visit within-subject study. Visit 1 consisted of familiarization, a one repetition maximum (1RM) test, and caffeine intake assessment. Visits 2-3 consisted of dominant arm BFR-RE [3 sets of bicep curls to failure with 30% 1RM, 40% arterial occlusion pressure (AOP), 30s inter-set rest]. Visits 2-3 were 1h after typical dose, one with caffeine (CAFF) and one without (ABS) (counterbalanced). Heart rate (HR), systolic (SBP) and diastolic (DBP) BP, and AOP were measured pre- and post-exercise and ratings of perceived exertion (RPE-E) and discomfort (RPE-D) after each set. Exercise volume (VOL) per set was calculated as load (kg) x reps. Bayesian RMANOVA were used to find the most probable model for SBP, DBP, HR and AOP (results are mean±SD). BF10=most probable alternative model versus the null. Bayesian paired t-tests were used to compare RPE-E, RPE-D, and VOL within each set (results are mean difference±SD). RESULTS: Main effects of time and condition for SBP (mmHg, BF10=17774.82) and DBP (mmHg, BF10 =298.2) indicated CAFF (SBP=121.4±11.0, DBP=84.4±10.2) was greater than ABS (SBP=116.7±10.6, DBP=80.8±9.1), and post (SBP=123.5±9.6, DBP=86.7±11.0) was greater than pre (SBP=114.6±10.6, DBP=78.5±6.2). A main effect of time indicated AOP (mmHg, BF10=1.461e+6) increased pre (134.9±17.8) to post (154.3±19.6). Moderate evidence of a main effect of time indicated HR (bpm, BF10 =3.3) increased pre (77.9±10.1) to post (84.0±13.6). Anecdotal evidence indicated no difference in RPE-E (AU) between CAFF and ABS for sets 1 (0.1±1.0) and 2 (0.0±0.8, BF10 both<.3) and weak evidence for set 3 (0.5±1.1, BF10=1.2). Anecdotal evidence indicated no difference in RPE-D (AU) between CAFF and ABS for sets 1 (0.1±1.4), 2 (0.5±1.8), and 3 (0.2±1.7, BF10 all<.5). Anecdotal evidence indicated no difference in VOL (AU) for sets 1 (8.5±27.5), 2 (1.5±7.4), and 3 (0.8±8.0, BF10 all<.5). CONCLUSION: In habitual users, caffeine may increase BP, but other cardiovascular and perceptual responses to BFR-RE may not be impacted.

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