One of my other passions in life in addition to music and sports is fitness. Ever since I was a little kid I loved running, lifting, and anything else that had to do with staying in shape. Mostly it was sports specific, to improve performance. But as I delved into it further I found myself becoming more and more interested in physiology, kinesiolgy, nutrition, and sports medicine (although I'm not a doctor). So much so that in my previous career I a was a personal trainer and owned a few fitness centers in San Francisco.
During my stint as a personal trainer/gym owner I had a general philosophy regarding fitness training that I not only incorporated into my own workout regimen but also imparted to my clients, and now fellow friends and triathlon teammates. The basic theory of my training structure was what I call incremental training. The principle behind it is to GRADUALLY increase the workload in one's workout program, avoiding dramatic increases in weight being lifted or even cardio vascular training. I use to say, "stimulate, don't annihilate". Let me explain.
When the human body is starting from an untrained state it is primed to realize dramatic fitness gains early on in the cycle. Typically the muscles are able to handle the load, although they may get sore, however the problem lies with the connective tissue, ie. tendons, ligaments, and cartlidge. When the body has been in a sedentary state for a long period of time not only does the muscle atrophy but so does the connective tissue. So when the body starts to increase physical activity typically the muscle is stronger than the connective tissue. What we saw happen frequently in the gym was that newbies would be so enthusiatic about embarking on their fitness routine that they would jump in head first and almost invariably end up injuring themselves. Why? Because the body wasn't prepared to handle the sudden increase in workload. That's where incremental training comes in.
When I work out I keep a journal. People in the gym's I've worked out at over the years joke with me about my "diary". I jokingly call my book, "One More Rep". I keep track of my workouts for a couple of reasons, 1. so that I can remember what I did the previous week and have a plan for the current workout, rather than going in aimlessly; 2. for motivation. Each workout I look at the last similar workout from the previous week. Then I set my goal for the current workout to be attaining one more rep per each exercise beyond what I did the previous week. Once I've achieved the targeted rep range I add a little more weight for the following week's workout. As little as 5 lbs, sometime as little as 2.5 lbs for smaller muscle groups, ie. biceps/triceps. By doing this "incremental training" I avoid injury (annihilation) but I STIMULATE the muscle enough to respond, thereby getting stronger. I also use this method of incremental training in my cardio vascular training as well. Over the years it has worked well for me. I've seen significant improvements in my race times AND I've avoided injury.
Now, I understand that this method not be amenable to all fitness buffs. If you are a competitive body builder you need to overload the muscle quite a bit more than what I'm prescribing here to get the results you're after. However, if you're a weekend warrior, or an endurance athlete I would urge you to incorporate the incremental training methods into your routine. I'm positive you'll be happy with your results.