I am young-ish and pretty stubborn so my input is only worth what you paid for it.
As other have stated, there are no wrong answers. Everyone is different and in different shape. I like to focus training on my legs and lungs because I feel like I end up being well rounded and prepared for the mountains with that approach.
For me personally, longer hikes are more a test of my joints and my feet. I train in a way that minimizes stress on my joints while working my lugs and legs as hard as I can. My joints and feet are always getting a workout when I am focusing on my lungs and my legs, but I don't specifically train to torture my joints. I have had arthritic-type joint issues since my early 20's, but have not problems in the mountains when I'm in mountain shape.
If I had the time to do 10-mile hikes regularly I absolutely would, but I favor making shorter hikes as difficult as possible so that I can get to failure more quickly. Your body can do way more than you think it can. A lot of what limits you is your mental toughness. My very first training hike of 2021 was a 17.8 mile overnight hike with over 4,000 feet of vertical gain. On that trip I was hurting physically and questioned why I was there. I didn't think I could keep going at times, but I pushed through and taught my brain that I can do it. I was sore afterwards, but mentally much stronger.
I personally never carry less than a 50# backpack when training. My goal is to reach near failure on every training hike. This not only develops your body, but it builds a mental toughness that is valuable when you are in the backcountry. I prefer to break myself at home versus on the mountain. If you break on the mountain you are much more likely to throw in the towel early. I've been there and learned that lesson the hard way. The 18-hour drive back home provides plenty of time for reflection
I try to find a 5-ish mile hike that I can do regularly that has no less than 1,000 feet of total vertical gain. That is sometimes hard to find depending on where you live. At home, I just walk back and forth down the hilly road we live on and it gets me pretty close to my 5 mile/1,000ft goal, but it really isn't hard hiking. I have a difficult trail that is about an hour from my house that I hike once a week leading up to a trip and I make sure that I am pushing my body and mind pretty hard on those trips. If I don't reach near mental failure on those hikes I am not pushing hard enough. My goal is to have at least a few sections in the hike where I am breathing really hard and a few sections where I have a chance to catch my breath. I like super steep hills (preferably something around 45 degrees) for this as they are more representative of what I face on my trips to the mountains. Steep slopes are where I have seen most of my hunting partners break.
I have found that my legs are always my weakest link in the mountains so I will intentionally select certain training hikes to not use trekking poles on just so that I am working my legs extra hard on a regular basis. I always use trekking poles with super heavy backpacks on difficult trails as the safety risk just isn't worth it to me. For 50# backpack I don't hesitate to leave the trekking poles strapped to my backpack.
I tried a progressive training schedule in 2021 and felt like that was the most well prepared for a big trip I have ever been. The goal of each hike is to achieve 5 miles, 1,000+ vertical feet, with a 50#+ pack. The last two weeks of training I think it is wise to replace one or two hikes with some other form of low impact cardio such as biking or swimming. If you push too hard and injure yourself right before a trip it could be bad news, but I think really torturing your body and mind right before the trip gives you an edge when you are actually in the field.
My training schedule:
5-8 weeks before trip I am hiking once a week
4 weeks before trip I am hiking 2 times
3 weeks before trip I am hiking 3 times
2 weeks before trip I am hiking 4 times
1 Week before trip I am hiking every day
Week of trip go kill something and bring it home and eat it.
I ended up backpacking 90 miles over 7 days on that 2021 elk hunting trip and only felt like I was working hard the day that we hiked 19.2 miles carrying out elk meat. The rest of the trip, while wet and cold, just felt like another training day for the most part.
I used to lift weights years ago, but ended up injuring myself pretty regularly. I stick to more practical and enjoyable exercise like hiking now.
For a point of reference, I am 34 years old, 6' and 180#.
