I’m Melissa, a Shopify Guru. we would not have direct links to particular dropshippers that supply activewear. However, I did find this really good article on dropshipping recommendations for 2017 if you wanted to check that out and see if there are any that may offer such products: Best Drop Shipping Companies
Have a look at those dropshippers to see if any fit your niche and target audience. If they do, check out our App Store to see if there is an integration there, or reach out to them to see if it is possible to integrate that way.
Below you will find some apps that are available and ready to integrate with your Shopify account to start selling:
Hope this information helps! You can reach out to the Guru team https://help.shopify.com/questions if you have any questions.
Have a great day!
Melissa | Shopify Guru