Good work buddy. PB's are always a wonderful thing to achieve
With the 'hop sprints' there are variations.
1. Knee high, very fast close 'runs' x 10 straight into the sprint. You can alternate the width of your footfall from narrow to wide during the knee highs if you want to engage add/abductors as stabilisers more.
2. Litvy squats: 5 deep plyometric squats straight into a 50m sprint. more advanced. 4 sets of this get you blowing like Darth vader with asthma
You wont find a bigger fan of sandbags, tires sledgehammers etc than me. If you enjoy them, and the training gives you results, then keep at it