some beginers asked me if sport need more strenght than trad. My point of view is that we use our strenght differently. In the discussion, we taught how can we estimate the strength of each climber? In many books, they use the relative strenght (the weight you can pull in one pull up divide by your body weight). The notion is very interesting as some study make a relation between your relative strenght (0.8 for women in the army in 1980 and 1.25 for the man) and the grade you can climb ( 4 pull up without extra weight and you can climb most 5.9). As the method is not precise and climbing a slab don't need as much strenght than an overhang, it is hard to use it.
In my opinion, we must compare the same person doing trad and doing sport. As actually most of the climber climb easily 5.10 or 5.11 in sport, and hardly 5.9 and 5.10 in trad, most people will conclud that it is easier in sport.
I don't think so. I think that we must compare the energy use in climbing. For example, imagine that you have 100 unity of energy and that you make three moves.
In trad, you will begin to climb, do the first move to a rest, place a pro, do the second move to an other rest, place a pro and finish with the last move. If you have 100 unity of energy, you will use 30 unit for the first move, 10 unit to place the pro, 30 unit for the second move, and 10 unit to place your last protection and you will fall in the last move because you just have 20 unit left and you need 30.
In sport, You will do the first move, clip the bolt, do the second move, clip the bolt and finish the third move. You are going to spend your energy like that: 30 + 5 + 30 + 5 + 30 = 100 unity.
So, in that example, sport climber do a better use of his energy because he just have to clip a bolt. Other strategy to keep your energy will be to learn the movement before, one at a time, and to try the sequences after. If you climb fast, you will loose less energy to keep your body in balance on the wall. To do that, some people will down climb a route and practice the movement. I saw some people coming to evaluate the route one year before he try to do it.
Trad have also there strategy. As the climber don't have enought energy (30 + 10 + 30 + 10 + 30 = 110), he will try to take rest. There is two kind of rest: active rest, the climber use aerobic strenght to recover is energy and climb very fast to use is maximal strenght for a short period or passive rest, the climber hang on the rope.
With that information, a beginer can understand why the climber favorise the strategy bottom up before. It is because the climber like to understand the move from under, use a strategy to keep is strenght and be prepare mentaly for a fall as he place is pro.
We can also understand that a sport climber will prefer to climb hard and was not as interested in placing gear. So, a sport climber who need 110 unity of strenght will climb a higher grade than a trad climber who need 110 unity of strenght. But the energy use will be different (aerobic, anaerobic lactique, anaerobic alactic and creatine phosphatase)