Results

Table 1 presents descriptive information on the 188 male and 176 female subjects according to supplementation group and exposure cohort. Mean ages do not differ significantly between treatment groups within cohorts. However, the small differences of up to 0.9 y (Cohort 3 females) were considered sufficient to include age as a covariate in all regression models that follow. Subjects in Atole villages tend to be taller and heavier than those from Fresco villages as reported by Rivera et al. (1995) for the whole sample. Differences are statistically significant for all measures in males and for height in females when all cohorts are combined and age is a covariate (data and analysis not shown). However, they tend to be nonsignificant when exposure cohorts are analyzed separately because of reduced statistical power. FFM is greater in Atole males compared with Fresco males in all cohorts, while differences in females were not seen. BMI is similar between both groups.

TABLE 1 Mean values for physical characteristics of Atole and Fresco subjects by cohort¹

Variable, group	Cohort 1	Cohort 2	Cohort 3
*Males*
Age, y
A	12.8 ± 1.1	16.8 ± 1.3	22.1 ± 1.9
F	12.8 ± 1.0	16.4 ± 1.3	22.6 ± 2.3
Height, cm
A	142.5 ± 9.8*	159.7 ± 9.3	164.2 ± 4.7
F	139.3 ± 8.7	156.4 ± 8.6	162.8 ± 7.5
Weight, kg
A	34.2 ± 6.2	48.1 ± 7.5	57.5 ± 5.4
F	32.5 ± 5.5	45.8 ± 7.7	56.1 ± 7.3
Body mass index kg/m²
A	16.7 ± 1.3	18.8 ± 1.5	21.3 ± 2.0
F	16.6 ± 1.3	18.6 ± 1.8	21.1 ± 2.0
Body fat, %
A	17.5±4.1	16.9±2.9	19.1 ±4.7
F	19.0 ± 5.0	18.0 ± 4.2	19.9 ± 4.9
Fat-free mass, kg
A	28.3 ± 5.7*	40.0 ± 6.1	46.4 ± 3.7
F	26.3 ± 4.7	37.5 ± 6.1	44.7 ± 4.5
Skeletal age minus age, y
A	-0.81 ± 2.66	-0.30 ± 2.19
F	-0.97 ± 3.05	- 0.45 ± 2.20
Sample size
A	33	44	24
F	25	42	20
Totals	58	86	44
Females
Age, y
A	12 ± 1.1	16.5 ± 1.4	22.5 ± 1.8
F	13.0 ± 1.0	17.2 ± 1.4	21.6 ± 1.8
Height, cm
A	143.2 ± 7.0	152.5 ± 6.2*	153.3 ± 5.1
F	141.3 ± 8.3	149.3 ± 4.6	151.3 ± 5.9
Weight, kg
A	35.7 ± 6.2	47.6 ± 6.0	49.2 ± 6.2
F	36.3 ± 7.4	47.7 ± 6.2	49.3 ± 5.5
Body mass index,kg/m²
A	17.3 ± 2.1	20.5 ± 2.5	20.9 ± 2.2
F	18.0 ± 2.4	21.4 ± 2.5	21.6 ± 2.6
Body fat, %
A	19.6 ± 3.5	22.6 ± 3.5	23.3 ± 4.0
F	20.6 ± 3.7	23.7 ± 3.4	24.5 ± 4.1
Fat-free mass, kg
A	28.5 ± 4.4	36.7 ± 3.9	37.5 ± 3.4
F	28.6 ± 5.0	36.3 ± 3.9	37.1 ± 3.2
Skeletal age minus age, y
A	0.19 ±2.60	-0.15 ± 1.01
F	-0.25 ± 2.19	- 0.02 ± 0.97
Sample size
A	26	34	21
F	35	40	20
Totals	61	74	41

¹ Values are means ± SD. Abbreviations used: A = Atole,F = Fresco.

* P<0.05, ** P<0.01, *** P<0.001 for two-tail t test of Atole-Fresco difference in means after adjusting for age.

Males tend to be delayed in maturation relative to the British children on whom the TW2 method is standardized, but their deviations from CA do not differ according to treatment (Table 1) Girls are less delayed than boys, especially in Cohort 2, where the small age deviations and reduced variances are due to a large number of girls having already achieved skeletal maturity compared with boy s. (66% vs. 16%). Because there is no significant difference by supplement type in SA within the two younger cohorts, subsequent analyses do not control for this variable.

Group means for physical performance measures at maximum exertion are presented in Table 2. The results of analysis of covariance controlling for age indicate that there are no treatment group differences in maximum heart rate, suggesting that both groups reached similar levels of exertion and that the heart rates along with Respiratory Quotient values are consistent with published velures, which suggests these subjects reached maximum exertion (Astrand and Rodahl 1986)

TABLE 2 Mean values for physiological measurements at maximum exertion in Atole and Fresco subjects by cohort¹

Variable, group	Cohort 1	Cohort 2	Cohort 3
*Males*
Maximum heart rate, beats/min
A	207.1±6.7	205.2 ± 6.3	201.9 ± 7.1
F	208.2 ± 5.2	206.0 ± 5.5	201.5 ± 7.8
VEmax [BTPS], L/min
A	61.8 ± 11.3	88.7 ± 18.7	103.0 ± 13.4
F	59.4 ± 12.0	83.0 ± 16.9	101.8 ± 21.1
VCO₂max [STPD], L/min
A	1.86 ± 0.45***	2.89 ± 0.62***.	3.29 ± 0.41
P	1.60 ± 0.34	2.43 ± 0.59	3.13 ± 0.45
VO₂max [STPD], L/min
A	1.70 ± 0.36**	2.62 ± 0.54.'	2.98 ± 0.31*
F	1.50 ± 0.30	2.24 ± 0.54	2.77 ± 0.39
VO₂max [STPD], mL/kg BW min ^-¹

A	49.5 ± 4.4**.	54.4 ± 6.4*,	52.0 ± 5.1
F	46.1 ± 3.9	48.6 ± 6.5	49.7 ± 7.1
VO₂max [STPD], mL/kg FPM min ^-¹
A	60.1 ± 6.2	65.5 ± 7.1***	64.3 ± 5.9
F	57.3 ± 6.7	59.2 ± 7.2	61.9 ± 6.5
RQ max
A	1.10 ± 0.06	1.11 ± 0.06	1.12 ± 0.08
F	1.08 ± 0.05	1.10 ± 0.06	1.15 ± 0.07
O₂ pulse, mL/beats

A	8.2 ± 1.7**.	12.8 ± 2.7**.	14.8 ± 1.7
F	7.2 ± 1.5	10.9 ± 2.6	13.8 ± 2.2
VE/VO₂ [STPD]
A	34.3 ± 3.2**	31.8 ± 4.3**	32.4 ± 3.9
F	37.3 ± 4.8	35.2 ± 4.4	34.3 ± 5.5
Sample size
A	33	44	24
F	25	42	20
Totals	58	86	44
Females
Maximum heart rate, beats/min
A	210.4 ± 6.4	208.3 ± 9.4	202.4 ± 8.5
F	208.7 ± 7.3	205.9 ± 6.8	202.1 ± 6.5
VEmax [BTPS], L/min
A	54.6 ± 9.4	69.4 ± 11.8	68.9 ± 9.4
F	53.3 ± 9.8	69.4 ± 11.3	69.3 ± 9.0
VCO₂max [STPD], L/min
A	1.56 ± 0.25**	2.02 ± 0.29*	1.98 ± 0.28
F	1.38 ± 0.28	1.85 ± 33	1.85 ± 0.37
VO₂max [STPD], L/min
A	1.40 ± 0.22*	1.74 ± 0.26	1.73 ± 0.21
F	1.29 ± 0.26	1.65 ± 0.31	1.63 ± 0.29
VO₂max [STPD], mL/kg BW min ^-¹
A	39.5 ± 3.8**	36.6 ± 4.0	35.4 ± 4.3
F	35.9 ± 4.1	34.5 ± 4.5	33.0 ± 4.6
VO₂max [STPD], mL/kg FFM min ^-¹
A	49.2 ± 4.2**.	47.3 ± 4.7	46.1 ± 4.8
F	45.3 ± 5.0	45.3 ± 5.8	43.7 ± 6.1
RQ max
A	1.12 ± 0.08	1.17 ± 0.07	1.16 ± 0.07
F	1.08 ± 0.08	1.14 ± 0.07	1.15 ± 0.06
O₂ pulse, mL/beats
A	6.7 ± 1.1*	8.4 ± 1.6	8.5 ± 1.0
F	6.2 ± 1.3	8.0 ± 1.6	8.1 ± 1.4
VE/VO₂ [STPD]
A	36.6 ± 4.8*	37.5 ± 5.1	37.4 ± 4.0
F	38.9 ± 5.4	39.9 ± 6.2	40.4 ± 5.6
Sample size
A	26	34	21
F	35	40	20
Totals	61	74	41

¹Values are means ± SD. Abbreviations used: A = Atole, F = Fresco, RQ = respiratory guotient.

* P<0.05, ·* P<0.01, *** P<0.001 for two-tail test of Atole-Fresco difference in means after adjusting for age.

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