Strength
- Loading Recommendations for Muscle Strength, Hypertrophy, and Local Endurance (pmc.ncbi.nlm.nih.gov)
Heart Rate Zones
- Heart Rate Zones Explained (health.clevelandclinic.org)
- Heart Rate Zones (polar.com)
- Understanding Heart Rate Zones for Effective Workouts (healthline.com, article cites more references)