To increase strength, what percentage of intensity based on 1RM and how many repetitions should a client perform?

The recommended approach to increasing strength is to train at an intensity level of 80-90% of a client's one-repetition maximum (1RM) with a repetition range of no more than 5-7 reps. This range is grounded in principles of strength training that emphasize lifting heavier weights with lower repetitions to effectively stimulate muscle hypertrophy and the neuromuscular adaptations necessary for strength gains.

Training at 80-90% of 1RM places significant demand on the muscular system, encouraging the muscles to adapt to heavier loads. This intensity level is optimal for promoting neuromuscular efficiency, enhancing motor unit recruitment, and improving overall strength. The lower number of repetitions ensures that the muscles are being worked to a high degree of fatigue, which is critical for strength development.

In contrast, the other options do not align with this principle for strength training. Higher repetition ranges with lower percentages of 1RM, as seen in the other options, typically focus more on endurance and muscle toning rather than maximal strength. Therefore, option B correctly embodies the effective method for increasing strength through the appropriate combination of intensity and repetition.