Based on the two choices I suggest that the client should be monitored on the side.
It is near impossible to accurately monitor someone if you walk on the treadmill next to them. If they:
A) Need to have the speed changed
B) Need to have the incline changed
C) Need A & B
D) Fall or trip on the belt
you are not in a position to provide proper assistance.
Being that we are only with our clients 2-4 hours/weekly; we try not to spend that time on the treadmill. Although we encourage various forms of aerobic training that’s suitable to the clients needs and capabilities, we don’t use that time as part of the client/trainer relationship. Most clients however, will have to be coached for proper form and to learn how to use frequency, intensity, and time to accomplish their objectives. That time is covered initially and monitored to make sure the client is being compliant to their program and not just watching TV, etc. You also need to be aware that when your clients are doing their aerobic activity, they are your responsibility when in your studio! Have an emergency plan in place and know what to do in any situation. We have a defibrillator just in case and think it’s a great investment for all studios, gyms, and clubs.
I use the treadmill for client assessment and some of my clients do their cardio on a treadmill, but I have never had a client do 30 minutes on the treadmill during a paid session with me.
When I’m assessing, I assess from all four sides of the client.
Most of my clients choose to warm up before meeting with me so they can get the most out of their hour. But if a client is warming up on the treadmill with me, I stand in front of the treadmill so we are face to face and I can talk with them easily without them having to turn to see me.
Use monitored treadmill time to visit with the client about goals and objectives, nutrition status, workout progress and challenges. Standing by also gives you the ability to monitor heart rate, rating of perceived exertion (RPE), incline, speed, their ability to talk and exercise . . . If you recently performed an assessment, they may be able to listen and review a summary of the results. It’s a good time to have them increase their heart rate while getting the chance to visit with them to build your personal relationship with them. Sometimes it’s hard to do that in a strength training or interval training session because you’re cuing motions, administering the workout, etc.