Executing a certain amount of rounds of a circuit or an AMRAP (as several rounds as you can) within a given time period are great techniques to get a killer conditioning work out in. The vintage spinal erector exercises are deadlifts and front squats. You can do dumbbell Romanian deadlifts, https://hammerstrengthdumbbells67899.blog2freedom.com/33277546/a-simple-key-for-hammer-strength-adjustable-dumbbells-unveiled