Spinal Cord Injury Level Influences Acute Plasma Caffeine Responses.
This study aimed to investigate the absorption curve and acute effects of caffeine at rest in individuals with no spinal cord injury (SCI), paraplegia (PARA), and tetraplegia (TETRA).



Twenty-four healthy males (eight able-bodied [AB], eight PARA, and eight TETRA) consumed 3 mg·kg caffeine anhydrous (CAF) in a fasted state. Plasma caffeine [CAF], glucose, lactate, free fatty acid, and catecholamine concentrations were measured during a 150-min rest period.



Peak [CAF] was greater in TETRA (21.5 μM) compared with AB (12.2 μM) and PARA (15.1 μM), and mean peak [CAF] occurred at 70, 80, and 80 min, respectively. Moderate and large effect sizes were revealed for TETRA compared with PARA and AB (-0.55 and -1.14, respectively) for the total area under the [CAF] versus time curve. Large interindividual responses were apparent in SCI groups. The change in plasma catecholamine concentrations after CAF did not reach significance (P > 0.05); however, both adrenaline and noradrenaline concentrations were lowest in TETRA. Significant increases in free fatty acid were seen over time (P < 0.0005), but there was no significant influence of SCI level. Blood lactate concentration reduced over time (P = 0.022), whereas blood glucose concentration decreased modestly (P = 0.695), and no difference between groups was seen (P > 0.05).



The level of SCI influenced the caffeine absorption curve, and there was large interindividual variation within and between groups. Individual curves should be considered when using caffeine as an ergogenic aid in athletes with an SCI. The results indicate TETRA should trial low doses in training and PARA may consider consuming caffeine greater than 60 min before exercise performance. The study also supports caffeine's direct effect on adipose tissue, which is not secondary to catecholamine release.
1Peter Harrison Centre for Disability Sport, School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, UNITED KINGDOM; 2Swiss Paraplegic Centre, Institute of Sport Medicine, Nottwil, SWITZERLAND; and 3School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, UNITED KINGDOM.
Terri Susan
TS
Graham-Paulson
Thomas Andrew William
TA
Paulson
Claudio
C
Perret
Keith
K
Tolfrey
Philip
P
Cordery
Victoria Louise
VL
Goosey-Tolfrey
D065567:Absorption, Physiological; D001786:Blood Glucose / Q000378:metabolism; D002110:Caffeine / Q000097:blood* / Q000493:pharmacokinetics; D004837:Epinephrine / Q000097:blood; D005230:Fatty Acids, Nonesterified / Q000097:blood; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D009638:Norepinephrine / Q000097:blood; D010264:Paraplegia / Q000097:blood*; D011782:Quadriplegia / Q000097:blood*; D013119:Spinal Cord Injuries / Q000097:blood*
D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D019344:Lactic Acid; D002110:Caffeine; D009638:Norepinephrine; D004837:Epinephrine