Effect of endurance training supplemented with green tea extract on substrate metabolism during exercise in humans

Abstract

Endurance training and ingestion of green tea extract (GTE), composed mainly of tea catechins (TC), are well known to enhance fat metabolism. However, their synergistic effects remain to be fully elucidated. We tested the hypothesis that endurance training supplemented with GTE would further accelerate whole-body fat utilization during exercise, compared with training alone, in humans. Twelve healthy male subjects [peak oxygen consumption (VO2peak), 50.7 ± 1.3 (SEM) mL/kg/min] were divided into two groups: GTE and placebo (PLA) groups. Subjects in both groups performed a cycle ergometer exercise at 60% of VO2peak for 60 min/day, 3 days/week, and daily ingested 572.8 or 0 mg TC in GTE and PLA groups for 10 weeks, respectively. Before and after training, respiratory gas exchange was measured during 90-min exercise at pre-training ∼55% of VO2peak. After training, the average respiratory exchange ratio during exercise remained unchanged in the PLA group (post-training: 0.834 ± 0.008 vs pre-training: 0.841 ± 0.004), whereas it was lower in the GTE group (post-training: 0.816 ± 0.006 vs pre-training: 0.844 ± 0.005, P<0.05). These results suggest that habitual GTE ingestion, in combination with moderate-intense exercise, was beneficial to increase the proportion of whole-body fat utilization during exercise.

Metabolic response to green tea extract during rest and moderate-intensity exercise

“…These changes suggest an enhancement in anaerobic energy metabolism. This result is somewhat unexpected since several previous studies have reported that acute [15] and chronic [16] GTE supplementation has the ability to induce greater fat oxidation rates over and above those of exercise alone, potentially through stimulating lipolysis as illustrated by higher concentrations of glycerol [15]. In the current study, no change in lipolytic metabolites (glycerol) was observed during exercise.…”

“…Chronic supplementation may induce a progressive regulation of various proteins and enzymes at certain sites in the body resulting in a systemic shift on the endogenous metabolism after long-term supplementation. For example, chronic GTE supplementation (8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24) weeks) has been demonstrated to alter the gene expression related to energy metabolism and lipid homeostasis in an animal model [40].…”

“…The administration of GTE could at least in theory have an additive effect on fat metabolism above and beyond what is seen with exercise alone. Indeed, it has been observed that fat metabolism is up-regulated during exercise following both acute [15] and chronic [16] GTE supplementation. So far, differences in the metabolic effects of GTE between rest and exercise have not been investigated in a single study.…”

Green tea extract supplementation does not hamper endurance-training adaptation but improves antioxidant capacity in sedentary men

“…Furthermore, colleagues (2005, 2006) demonstrated that exercise training (5 days/week) plus GTE feeding significantly prolonged endurance exercise time by ϳ8%-24% and that this improvement might be mediated through increased lipid oxidation in rodent skeletal muscle (Murase et al , 2006. Likewise, Ichinose et al (2011) also reported that daily GTE ingestion (572.8 mg/day), in combination with endurance training, was beneficial to promote fat utilization during exercise in human. The ability to enhance availability and utilization of free fatty acids during exercise would be crucial in sparing intramuscular glycogen and to reduce lactate production, which would positively contribute to an improvement in endurance capacity (Holloszy and Coyle 1984).…”

Influence of green tea catechins on oxidative stress metabolites at rest and during exercise in healthy humans

“…While, Ichinose et al concluded that daily GTC consumption (catechins, 572.8 mg; of which 100.5 mg EGCG; low caffeine, 76.7 mg) for 10 weeks of exercise training (3 days/week), significantly enhance fat oxidation (P<0.05) during moderate intensity exercise (60% VO 2 max), compared to placebo group [19]. While Ota et al finding suggests that chronic ingestion of GTC may result in up-regulation of fat oxidation during regular exercise in healthy male adults [20].…”