Table 1.

Evaluation of Possible Factors in Explaining the Observed Child—Adult Differences in Muscular Performance and Metabolic Response to Exercise

Observed Differences (Dimensionally normalized; relative to adults)		Factors
		Muscle Anatomy		Muscle Metabolism	Muscle Function
		↓ Relative Muscle Size	↓ Type-II Muscle-Fiber Composition (*)	↓ Anaerobic, ↑ Oxidative Profile	↑ Agonist- Antagonist Co-Activation (**)	↓ Intra-Muscular Synchronization	↓ Volitional Muscle Activation	↓ Type-II Motor-Unit Activation
Acute Exercise	↓ Maximal Isometric Strength	√	√√	—	--	√	√√	√√
	↓ Short-Term Power	√	√√	√√	√√	√√	√√	√√
	↓ Force Kinetics	—	√√	—	√	√√	—	√√
	↓ Force-Velocity Relationships	—	√√	—	√	√√	—	√√
	↓ Q30 & Mean Power Frequency	—	√√	—	—	√√	—	√√
	↑ Muscle Endurance	—	√√	√√	—	√	√	√√
	↑ Recovery	—	√√	√√	—	—	√	√√
Response to Resistance Training (non-hypertrophic)		—	—	—	√	√	√√	√√
Metabolic Responses	↓ Peak [La]	√	√√	√√	—	—	√	√√
	↑ Lactate Threshold in Blood & Muscle	—	√√	√√	—	—	√	√√
	↑ Intra-Cellular Pi/PCr Threshold	—	√√	√√	—	—	√	√√
	↑ Intra-Cellular PCr-Recovery Kinetics	—	√√	√√	—	—	√	√√
	↑ Fat, ↓ CHO Utilization	—	√√	√√	—	—	—	√√
	↑ VO2 Kinetics	—	√√	√√	—	—	—	√√

‘*’ - Assuming the possibility that the type-I ber composition of prepubertal children is higher than that of adults by as much as 10–15%.

‘**’ - Differences in coactivation may account for part of the observed strength child-adult difference in multijoint and dynamic movements, but apparently, not in single-joint, isometric contractions.

‘↓’ - Lower in children

‘↑’ - Higher in children

‘—‘ - Marginal or no effect

‘√’ - Can provide partial explanation

‘√√’ - Can provide full explanation