In a multicenter trial in Canada , we randomized 301 patients with breast cancer initiating chemotherapy to thrice weekly , supervised exercise consisting of either a standard dose of 25 to 30 minutes of aerobic exercise ( STAN ; n = 96 ) , a higher dose of 50 to 60 minutes of aerobic exercise ( HIGH ; n = 101 ) , or a combined dose of 50 to 60 minutes of aerobic and resistance exercise ( COMB ; n = 104 ) .