Regarding bone and tendons
First, let us assume that the physical parts of the body can handle the additional strength. A 175 lb trim person can bulk up to 250 lb and triple their strength in most weight-lifing measures; 50 lb + weight gains are par for the course for professional NBA or NFL players. This is accomplished while not breaking any bones or tearing any tendons (usually, though such injuries are relatively more common in pro athletes). However, this person's agility and movement is now limited by their new weight.
The chief advantage of this magical strength blessing is the increase in power to weight ratio. If you could maintain your 175 lb mass but triple your strength, you would see significant benefits in speed and agility. Now to use a sports analogy, just because you are 175 lb but as strong as a 250 lb defensive end doesn't mean you can do what a defensive end does. Your mass is still low, and mass counts for a lot in certain kinds of combat (such as blocking NFL linemen, or tackling). However, if you are 175 lb and as strong as a 250 lb NBA power forward, or NFL running back, you will see the large returns on your agility.
So regarding combat overall, it depends on what you are doing. Getting stronger won't help you as much in combat that depends on the push (locking shields Greek phalanx style, or charging an opponent with a couched lance) but will help you a lot when you can combine strength with agility (shooting a composite bow from horseback, throwing javelins, or dueling with swords)
Running is limited by the force of gravity pulling you down. You take a stride and then you have to be pulled to the ground by gravity in order to make contact with your next stride. Increasing your stride rate is an option, but not as good of one: increased rate causes increased friction and will cause cooling problems. Someone with a magical strength blessing would be better off looking somewhat like the astronauts on the moon, hopping around with unbelievable stride lengths. However, this would take some time to get used to, and you might not really be able to utilize your full power.
Jumping is much more straightforward. The work done by a jump is force times distance; if your legs are just as long and the force increases by a factor of 3, then the distance increases by a factor of three.
The work done by the jump will all be converted to potential energy at the height of the jump. So $F\cdot d = m g h$. Since distance, mass, and gravity are all constant in this case, force is proportional to the height jumped. If you can jump with three times more force out of your muscles, you can jump three times higher. An impressive initial box jump of 1 m would turn into an unbelievable box jump of 3 m.
Unfortunately, as @JasonK points out in the comments, landing from a 3m fall isn't exactly trivial. Humans just don't jump that high. You may have enhanced strength, but you don't have enhanced durability. Even if you have good technique, jumping this high frequently will get you a sprained ankle or stress fracture sooner or later.
Grappling is something where you will be limited by mass. Instead of the ratio of your power to your weight, what matters is the ratio of your power to your opponents weight (and his power to your weight). For example, if the 175lb trim blessed warrior is 20% stronger than his 250 lb opponent, he is still at a disadvantage due to the mass disparity being more than 20%, assuming fighting skill is equal. This would be the classic MMA battle of striker vs. wrestler, where your blessed character would work hard to avoid the ground and pound. Climbing wou
Climbing, punching, kicking, pulling, and pushing should all scale about linearly with increased strength, at least for reasonably small strength gains like a factor of 3.