There are basically 3 types of workouts ( I am sure some here can argue this), Strength training (generally builds muscle mass), aerobic/cardio, and endurance. IMNSHO, they are all important. I was fortunate enough in high school to be trained by Bob Whelan. That however was decades ago, as like you I am now in my 50's. That training however, has lasted me a lifetime, and seriously benefited me through several injuries. I can't say that I have fully recovered from my injuries, but I can out perform 95% or more of the men in my age group. But before I get into workouts, I'd like to suggest that if your not already using a premium hunting pack, designed to haul heavy loads, then you should do so.
Strength training (isotonic strength training) Or better know as weight lifting, does exactly as the name implies, it builds stronger muscles, enhances definition, and can build , muscle mass. It should be obvious that the benefit derived can greatly depend on diet, as if your not taking in the calories and protein to build muscle, you can, well, lose weight, while still gaining definition (burn through your fat reserves). Most people do not utilize proper technique, i.e., they do not take advantage of resistance training when lifting. One such example is the bench press. Most people do the lift, even arching their back (poor technique and not compliant with competitive rules), then they let the weight fall back down to their chest, stopping it just before it lands on them. In proper technique you slowly raise the weight/bar, and slowly lower it; it's a controlled lift and decent of the weight/bar.
Aerobic/cardio, and endurance have overlap, but I am going to stick with separate definitions, Old studies indicated that to attain an aerobic benefit, one need to maintain an elevated heart rate for a minimum of 45 minutes. More recent studies put that at 30 minutes (if I recall correctly). You can do this in strength building by simply moving from one lift to the other with no breaks, no lallygagging... Your pack walks obviously do this also, as long as your going for30 minutes or longer.
Endurance training pretty much always includes aerobics, as your simply training to continue an activity or activities for a prolonged period of time, at an heightened rate. Pretty much what many of us do hunting. It doesn't build large muscle mass, although you can increase muscle mass from this type of workout. What it really does if your doing a comprehensive endurance workout is make you ripped and lean. But if you want to perform at your best (from a hunting perspective, you need a balance of all 3.
When we a re hunting, we are not walking on flat ground, as such to avoid injury our muscles need the strength to make adjustment to uneven terrain, slips... however if we don't have endurance to last the duration, those muscles will give out, sometimes when we need them most (to avoid injury). This is where that endurance training comes in. But keep in mind that avoiding injury takes more that just strong legs, you also need a strong core, along with excellent balance. From what you wrote, it sounds like your concentrating on strength training, in preparation for carrying out the meat of an animal. If your huffing and puffing your likely getting an aerobic benefit, but it sounds like your lacking on the endurance end of at this point in time. What I mean is that your not walking at an accelerated pace. Don't be discouraged, as it takes to improve. But I would suggest to through some jogging in there at least every other day, with no weight/pack, as you want to build up you wind, as depending on how far you want to go with with this, eventually work up to running bleachers.
Personally, I think that high paced endurance training is way underrated by most hunters. Okay, what do I mean. I mean that in pursuit of the animals we pursue, we often need to move at a pace that raises our heart rates for prolonged periods of time. But furthermore, when we go to shoot an animal, whether we are shooting a bow or a gun, we need to be able to hold steady to make a precise shot. The greatest benefit for doing this comes from high paced endurance training i.e., high aerobic endurance training. For evidence of this just look to our military special forces, many of which are stuck on ships at sea for months on end. Many of those ships are not equipped with weight rooms. In such cases, our special forces utilize a high paced aerobic/endurance resistance model to maintain total body fitness.
At 52, I know that you might not be looking at getting in top shape, but I do hope that this information is useful in determining a suitable workout.
