The short answer is no. If your diet provides sufficient micronutrients, additional vitamins or minerals will not alter performance. All stress (including exercise) requires additional nutrients because the body pushes through the water soluble vitamins faster than fat soluble vitamins or minerals. If you are eating a balanced diet then minimal additional stress – like that produced by mild to moderate exercise – probably do not require additional nutrients. If the micronutrients in your diet can not keep pace with your daily exercise routines then it is reasonable to add a small amount of B or C vitamins. The danger zone appears in adding too much which tends to put a huge burden on the kidneys. This can also be problematic if clients are taking anti-inflammatory medications such as ibuprofen because the latter tends to alter resorption of electrolytes via the kidneys increasing the probability of bad long-term side effects.
Muscular activity is heavily reliant on sufficient calcium and magnesium – which cannot be absorbed properly without Vitamin D. There should be sufficient in the diet of any client eating a wide range of foods that include dairy products. If you have vegan clients then a quick review of their nutritional regimen should help determine any gaps.