[citation needed] I'm mid-40s and have no problem doing low-rep high-resistance (> 85% 1RM) sets 2-3 days per week and alternating with 2-3 HIIT sessions on bi

[citation needed] I'm mid-40s and have no problem doing low-rep high-resistance (> 85% 1RM) sets 2-3 days per week and alternating with 2-3 HIIT sessions on bike, run, or swim for triathlon training. You have to decide what your goals are (endurance = 12+ rep sets at 30-50% 1RM, hypertrophy = 8-12 rep sets at 55-75% 1RM, strength = 1-6 rep sets at 85% - 100% 1RM) AND you have to have excellent form for the prime mover exercises (deadlift, squat, bench press, bent-over row) to avoid injury, but with the right diet, discipline, and proper recovery consistent 5% gains per three- to four-week cycles are possible Reference: _Periodization Training for Sports_ by Bompa, http://www.humankinetics.com/products/all-products/periodization-training-for-sports-3rd-edition http://www.humankinetics.com/products/all-products/periodiza...