If you want to build powerful, toned quads, leg extensions are a classic isolation exercise featured in most leg day strength programs. But what happens when you do 60 reps every day for a week? I have found that.

But first, doing isolation exercises every day is not the best way to build strength and muscle throughout the body. Over time, such exercises can overtax the muscles and associated joints. To allow the muscles to repair themselves, at least 24 hours of recovery should be included between leg day workouts, opting instead for upper body workouts and active recovery days. For this challenge, however, I wanted to try high reps for only one week.

Isolation exercises, as the name implies, fatigue a single muscle group, whereas compound exercises (such as squats and lunge) target multiple muscles and joints together. In the discussion of single-joint versus multi-joint resistance exercises (open in new tab), a reasonable strength and conditioning program will employ a progressive overload technique that mixes both, with an emphasis on compounds, as accessory movements for larger lifts. Add isolation exercises.

Keep a set of your best adjustable dumbbells on standby for leg extension exercise variations.

Like hamstring curls, leg extensions are usually performed on machines in the gym, but that makes the exercise less accessible to those with limited equipment. Dumbbell leg extensions can create size and definition in the quads and can be performed anywhere with one or two dumbbells. Free weights can also be used to eliminate muscle imbalances and improve cross-body coordination.

This method is easy to follow for beginners and will teach you the correct way to move to better support your back. However, it can strain your stronger side (we all have one or the other) and can create imbalances.

Leg extensions with dumbbells require more balance, core activation, and better posture. Both methods can be added at the end of a strength training program when muscles are already tired from compound exercises such as squats and deadlifts. Drop sets (increasing the number of reps with decreasing weight or reps) can be employed, or you can aim for a maximum number of reps before burnout.

Never swing your legs or throw weights. Always move with control. If you cannot extend your knees, decrease the weight to increase range of motion.

Leg extensions strengthen the quadriceps and knee joint attachments. Complete knee flexion and extension builds strength and muscle tone.

I used dumbbells for this fitness challenge and worked on 6 sets of 10 repetitions. I concentrated on squeezing my quads hard at the top, paused briefly, and then slowly lowered the weight. The last few reps of each set had to be squeezed to the last drop. Isolation exercises are to be done with all your might.

If you have a knee injury, suffer from arthritis, or have a narrow range of motion, always check with a medical professional before performing leg extensions and stop if you feel pain.

Leg extensions have a bad reputation for injuring the knees, but there are two ways to look at this. For many people, leg extensions are a great exercise to strengthen the muscles around the knee joint and protect against injury. Strength exercises may also help develop muscles needed for sports such as soccer (think of how you kick a ball) and sprinting.

Knee pain is almost always the result of ankle loading and stress on the knee. Overloading the muscles and tendons is one of the causes, which can sometimes be remedied by lifting lighter weights. High repetitions and daily repetitions were certainly too much for me, so I dropped to a lighter load than I normally use. I was able to focus on the full range of motion without overworking my knees and felt much more comfortable while working my quads hard.

Here are some great exercises for strengthening the knees and yoga for knee pain.

Leg extensions with machines help improve posture by allowing the back to rest, while dumbbell leg extensions with a flat bench require the core muscles to be engaged in order to sit up straight. I noticed I was leaning forward excessively, so I spent the rest of the day in front of the mirror watching my form.

Initially, I felt pressure being sent to my lower back and noticed that my pelvis was rounding toward my spine. After a brief adjustment and periodic checkups, my core felt as if a switch had been flipped and I was incredibly sore. Also, progressive overload (gradually adapting variables such as reps and weight over time) did not happen in a week, but felt more comfortable as the weeks progressed.

There was little to no shock, but the quads were quite weak during CrossFit workouts throughout the week and the legs felt overworked.The Journal of Physiology (opens in new tab) has found that micro-tears in the muscles during exercise can cause DOMS (delayed onset muscle soreness The Journal of Physiology (opens in new tab) explains that micro tears in muscles during exercise are the primary cause of muscle soreness known as DOMS (delayed onset muscle soreness).

We cannot stress enough how important rest and recovery are to aid in muscle repair, recovery, and growth. Always allow at least 24 hours after a lower or upper body strength training program to target alternating muscle groups throughout the week to avoid overtraining.

Next up: core 5 dumbbell exercises and core 5 barbell exercises to build strength, muscle, and power. Add these compound movements to your workout routine and mix in isolation exercises for a full-body workout.

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