The purpose of this investigation was to study a high-intensity resistance exercise overtraining protocol resulting in muscular strength decrements. Seventeen weight-trained males were divided into an overtraining group (OT; N = 11; mean +/- SE, age = 22.0 +/- 0.9 yr,) that exercised on a squat machine daily for 2 wk with 100% of 1 repetition maximum (RM) relative intensity, and a control group (CON; N = 6; age = 23.7 +/- 2.4 yr) that exercised 1 d.wk-1 with low intensity (50% 1 RM). Test batteries were conducted at the beginning (test 1), after 1 wk (test 2), and after 2 wk (test 3) of the study. One RM performance significantly decreased from test 1 to test 3 (P < 0.05) for the OT group (mean = -12.2 +/- 3.8 kg), but not the CON group (mean = -1.1 +/- 0.8 kg). Isokinetic and stimulated isometric muscle force significantly decreased for the OT group compared with the CON group by test 3. The primary site of maladaptation appeared to be in the periphery as indicated by changes in stimulated force, circulating CK activity, and exercise-induced lactate responses. This protocol produced a significant decrease in 1 RM performance, thus providing a model for the study of short-term, high-intensity resistance exercise overtraining.