Daily consumption of tea catechins improves aerobic capacity in healthy male adults: a randomized double-blind, placebo-controlled, crossover trial

Figures & data

Table 1. Characteristics of study subjects

	Value
Age, (years)	33.9 ± 7.4
Body weight, (kg)	67.6 ± 8.6
Height, (cm)	173.6 ± 7.6
Body mass index	22.4 ± 1.4

Note: Values are means ± SD (n = 16).

Table 2. Catechin compositions of the test beverages (mg/500 mL).

	Control	Catechin
Catechin	0.0	12.7
Epicatechin	0.0	49.7
Gallocatechin	0.0	36.0
Epigallocatechin	0.0	174.7
Catechin gallate	0.0	4.1
Epicatechin gallate	0.0	65.7
Gallocatechin gallate	0.0	9.1
Epigallocatechin gallate	0.0	218.4
Total	0.0	570.4

Table 3. Composition of the test beverages.

	Placebo beverage	Catechin beverage
Catechins (mg/bottle)	0	570
Caffeine (mg/bottle)	15	15
Nutrition facts
Energy (kcal/bottle)	17	17
Protein (g/bottle)	0	0
Fat (g/bottle)	0	0
Carbohydrate (g/bottle)	8	8
Total volume (mL/bottle)	500	500

Table 4. Changes in anthropometric variables before and after the intervention.

	Baseline		8 weeks
	Placebo	Catechin	Placebo	Catechin
Body weight, (kg)	69.7 ± 9.8	69.5 ± 10.3	69.5 ± 10.3	69.2 ± 10.2
Body fat ratio, (%)	18.2 ± 4.4	18.1 ± 4.6	18.0 ± 4.4	17.7 ± 3.4
Whole BMM, (kg)	53.7 ± 5.5	53.6 ± 5.8	53.8 ± 6.0	53.9 ± 6.3
Leg muscle mass, (kg)	9.6 ± 1.2	9.6 ± 1.2	9.6 ± 1.3	9.5 ± 1.4

Notes: BMM, body muscle mass. Body weight, body fat ratio, whole-body and leg (average of left and right) muscle mass were measured using a bioimpedance body fat analyzer (BC-621, Tanita, Co., Tokyo, Japan). Values are means ± SD (n = 14). There were no significant differences between the groups and the changes within each group from baseline.

Table 5. Physical performances of the subjects before and after the intervention.

		Placebo	Catechin	p-Value^a
VO2max, (mL/min/kg)	Baseline	38.9 ± 5.6	39.5 ± 5.6
	8 weeks	45.0 ± 6.5^*	45.3 ± 8.7^*	p = 0.206
VT, (mL/min/kg)	Baseline	15.9 ± 3.0	15.8 ± 2.1
	8 week	16.6 ± 3.2	18.0 ± 4.5^*	p = 0.006
Leg extension strength, (Nm)	Baseline	170.4  ± 24.0	168.3 ± 21.4
	8 weeks	172.3 ± 23.0	178.2 ± 23.0^*	p = 0.057

Notes: VO₂max, maximal oxygen consumption; VT, ventilation threshold. Values are means ± SD of 14 subjects.

^a The p value indicates differences in the study endpoints between the interventions, as evaluated using the Bonferroni test after analysis using a linear mixed model, with group, period, period baseline, and the interaction of group and period as fixed effects, and subject as a random effect.

^* p < 0.05, significant difference compared with the baseline by the paired t-test.

Fig 1. Recovery rate of oxygenated hemoglobin/myoglobin (oxy-Hb/Mb) level of the exercising muscle during the cool down after the graded exercise session during the aerobic capacity test in the placebo group (A) and the catechin group (B). Values are means ± SD. * p<0.05, significant difference compared with the baseline by using the paired t-test.

Table 6. Changes in post-exercise blood variables before and after the intervention.

		Placebo	Catechin	p-Value^a
Lactate, (mmol/L)	Baseline	2.34 ± 0.74	2.38 ± 0.66
	8 weeks	2.19 ± 0.89	2.03 ± 0.47^*	p = 0.119
Glucose, (mg/dL)	Baseline	88.4 ± 8.5	88.6 ± 6.2
	8 weeks	88.2 ± 7.8	86.2 ± 7.1	p = 0.469
NEFA, (mEq/L)	Baseline	172 ± 51	194 ± 48
	8 weeks	210 ± 82	205 ± 67	p = 0.144

Notes: NEFA, non-esterified fatty acid. Values are means ± SD of 14 subjects.

^a The p value indicates differences in the study endpoints between the interventions, as evaluated using the Bonferroni test after analysis using a linear mixed model, with group, period, period baseline, and the interaction of group and period as fixed effects, and subject as a random effect.

^* p < 0.05, significant difference compared with the baseline by the paired t-test.