It could be just coincidental, but part of my getting-faster training strategy was working out in the gym. This was in my 50s and I had riding buddies who were younger and faster than I on the climbs. This is not what you'll usually see advised on BF, but it worked well for me. These workouts were right out of The Cyclist's Training Bible. I only did the AA stuff in the attached doc, circuit style, during gym low population hours. I did 1 set of 30 for a month, then 2 sets of 30 for a month, then 3 sets of 30. I used the same weight for all the sets of the same exercise, except for squats and leg sled where I used a normal succession of weights . Regardless of the number of sets, I used a weight with which I couldn't quite do 30 on the last set. I worked out twice a week in the fall and once a week in the spring.
Of course at the same time, I was riding my guts out with my group once a week, chasing those youngers up every hill, and doing zone 2 rides on weekdays. It took a couple years, but I eventually did get fast enough to ride with the leaders.
