I would definitely agree with Joanne that this is a tricky one. I’m going to assume that by “tone” you mean “create lean, sleek muscles.” Is that fair?
I get this question or concern a lot from women, in particular. Usually what is meant is that the person would like to “see” muscles and have a firm appearance and feel. There are a number of factors that go into actually having sleek, defined, hard muscles.
Hormones and water retention might be the two things that have the biggest impact on this. People with higher levels of testosterone tend to have “harder” muscles in that they do “feel” harder when they are flexed. Remember that all muscles are “hard” when flexed. Estrogen level is something that can affect water retention. More estrogen generally leads to more water retention. This is potentially one of the reasons that it is much easier for males to get “toned” than it is for women, generally. It’s also one of the reasons that males can build so much more muscle. Without going too much into the science of it all, testosterone can convert to estrogen, but the testosterone/estrogen ratio is higher in men, and the estrogen/testosterone ratio is higher in women. Simple enough.
Water retention isn’t necessarily a bad thing. Muscles need to be hydrated. A healthy person who is extremely fit may appear average depending on the level of hydration. More fluid in your muscles translates to a smoother look. I think some people call this “Swoll.” =) Being “Swoll” results from your body shunting blood and fluid to your muscles during exercise. This effect wears off quickly once training has concluded. If you don’t stretch and do a proper cooldown, some of the fluid built up in your muscles doesn’t have an opportunity to redistribute, and that can lead to Delayed Onset Muscle Soreness.
1.) In regards to higher reps and less weight for toning, I can tell you that the tendency for people who train with heavy weight and fewer reps is to have bulkier, smoother muscles. This training is good for hypertrophy, or increasing size of muscle cells. People who train heavy can also experience a small boost in free testosterone levels.
2.) People who tend to train lighter with more reps tend to have sleeker, defined muscles. I remember reading somewhere, I can’t give you a source on this, that there is some debate over whether or not this type of training can be used to encourage hyperplasia, or increase in number of muscle cells. Natural hyperplasia doesn’t tend to result in much “bulk” gain. Notice I said natural. Hyperplasia is not common after puberty. By the time puberty is over, you more or less have what you’re going to have. The research shows that people don’t tend to create more muscle cells after a certain period of time.
As Joanne mentioned, the first method of training is more for power, the second method of training is more for endurance. Endurance athletes tend to be leaner and “skinnier” than power athletes. They also tend to have a moderate level of definition.
Probably the best middle ground that I demonstrate here is bodybuilding. Bodybuilders find that relatively high weight with a moderate amount of reps (8-12) is ideal for building both mass and definition in muscles. Bodybuilders often do 4-6 exercises per muscle group with relatively high weight, a moderate amount of reps, and a healthy number of sets 3-6.
Someone looking to tone might also consider diet. Certain foods are not conducive to sleek musculature. The amount of sodium in your diet tends to be a big factor relating to excess water retention. I believe 2000 miligrams per day is the current recommended dietary allowance.
To answer your question, I would say that there is no definitive answer as to whether or not higher reps with less weight would be good for toning. I wouldn’t be comfortable with saying that there is a cause and effect relationship here because I can’t be certain of the science on this matter at this time, but I will say that in my experience, there is a strong correlation between toning and training with lighter weight and more reps (12-18 reps).
Everybody is unique and Every Body is different.
Does this help at all?