The Best Two Exercises for Legs

Best Two Exercises, Simplified

For the true adductors, I chose the barbell squat and the seated hip adduction machine. These two exercises really have no competition in terms of EMG. The copenhagen adduction is the only thing that challenges the seated hip adduction machine, but the exercise can’t easily be made more difficult, so it was disqualified. The choices for these exercises were no brainers, but finding research on the adductor group was quite difficult. 

The barbell squat is a cornerstone exercise that can make total body composition changes. It’s a loaded version of a fundamental activity. The squat is likely the second most important exercise to do, behind the deadlift. Yet, combining the squat and deadlift creates a perfect blend of exercises and the only problem with doing them often is the demand they place on the lower back. They are both also extremely technically demanding and the squat requires a high amount of coordination. A technically sound squat involves the participant keeping the barbell over their center of gravity, having spinal neutrality, sitting low enough so that the crease of the hip is below the knee, using the whole foot as a base of support, moving the barbell in a straight line, keeping knees over feet, and keeping the neck as neutral as the spine. 

The seated hip adduction machine is a simple machine. It’s not a complex barbell movement and doesn’t require any balance. Functional trainers might poo poo this, but it’s quite a capable strengthening and injury preventative exercise. One consideration is not overstretching the groin while doing the activity. Opening your legs to create a 90 degree angle will suffice for most people. 

Boring Sciency Stuff

The adductor group is the area commonly referred to as the groin muscles. It’s comprised of the adductor magnus, adductor longus, adductor brevis, gracilis, pectineus and obturator externus. There are numerous functions of the muscle group, some of which don’t involve hip adduction. The pectineus is a hip flexor and the obturator externus is a hip extensor – sometimes considered apart of the gluteal region. I am disqualifying the pectineus and obturator externus because they’re not hip adductors, but they will make an appearance in the hip flexor portion of this series. The adductor brevis won’t be considered because there is no research on the EMG of the muscle. And the gracilis will be seen as a supplementary adductor to the AL – the gracilis is highly activated at a hip flexion angle of 70 degrees, which is likely the hip angle a participant would have during the seated hip adduction machine [34]. 

The barbell squat was an obvious choice for the AM considering it’s a powerlift, bipedal exercise, extremely effective activator of the quadricep group and magnus. The adductor magnus is the largest of the groin muscles and the second largest muscle in the body. The adductor magnus is special, as it connects at two key points: the medial and posterior portion of the thigh. The primary function of the adductor magnus is hip extension with flexed hips and has a secondary role during leg of adduction. This is elucidated by research evaluating the emg of a single leg machine hack squat: the AM had an extremely high EMG compared to the AL [29]. No research could be found on the lunge or barbell hip thrust. One study evaluated the adductors during the deadlift and sumo deadlift but didn’t delineate between the specific adductor muscles and the results concluded relatively low adductor activation [21]. Based on the function of the AM, the deadlift would be a submaximal way to develop the magnus considering the hips would likely never reach full flexion. Another article evaluated the AM during the barbell squat, it had promising conclusions but stands alone. The most difficult part of the squat is when the hips are at their highest point of flexion. Therefore, the AM may be considered the primary muscle of the squat, as the EMG of the AM is equal to the VL. Unless you’ve strained your groin, you likely don’t understand how important the AM is during the squat. 

The data, collected by Zink et. al, analysed muscle groups during the squat while either wearing a weight belt (Down WB and Up WB) or not wearing a weight belt ( Down NW and Up NWB). The primary muscles of the squat seem to be the VL, AM, and ES, as they were activated highly during descent and ascent. 

The second choice for the adductors is focused on adductor longus (AL) activation. The seated hip adduction machine has the highest activation of the dominant and non-dominant AL. Although in the same region, the function, size and joint connection of the AL is different than the AM. The only function of the AL is to adduct the hips and It’s much smaller than the AM. Because it has one function and is much smaller than the AM, the AL is injured often in sports. Most research on the AL is centered around soccer and groin rehabilitation. Considering the torque of the soccer instep requires a great deal of groin strength, it’s no wonder protocols have been developed to rehabilitate and prevent groin injuries specifically for soccer players. The unifunctional AL should be a consideration for all athletes who employ explosive diagonal or side to side motions. The hip adduction machine had high AL activation and was relatively equal between both legs. The reason isometric adduction wasn’t considered is exactly because it’s isometric. The adduction machine has the benefit of progressive overload – while the copenhagen adduction and isometric adduction don’t – and, more importantly, employs the stretch shortening cycle. The exercise also doesn’t involve the lower back so it can safely be paired with any of the other activities discussed in this series.  M 

The data, collected by Serner et. Al, evaluated the EMG of multiple exercises targeting the adductors [28]. The research doesn’t show the hip adductor machine to have the highest peak, but it was chosen for its ability to progressively overload and the equivalent emg between legs.

In an effort to save the natural lifter time and energy, I’m going to pick two exercises which have the highest muscle activation in the lower body. Unless you’re a juice up horse with a needle in your butt, you don’t need to spend two hours in the gym to maximize efficiency. Once you trigger muscle protein synthesis, it’s time to leave the gym. The idea that a natural lifter needs 20 sets of 5 different exercises all targeting the same muscle group is misguided time wasting. I will try my best to avoid choosing the same exercise in different muscle categories. Five categories will be considered: the quadriceps, hamstrings, glutes, hip adductors, and hip flexors. Exercises will be evaluated by their electromyographical (EMG) amplitude. EMG is recorded by placing electrodes on muscle groups in an effort to record electrical impulses. EMG can be described as the study of electricity in muscles. More specifically, EMG amplitude is a measure of motor unit activity during muscle action. It’s described as an evaluation of muscle tension or how hard a muscle becomes during exercise. EMG comes with a set of limitations: cross talk, interference, placement error, muscle fatigue, technique, etc. Researchers plan for this and typically make every effort to avoid these limitations.

Colloquially called the thigh, the quadriceps are so named for it’s comprised of four muscles. The vastus medius (VM) lies on the inside of the thigh and connects to the knee joints. The vastus lateralis (VL) runs up the outside of both thighs. The rectus femoris (RF) and vastus intermedius (VI) run up the middle of the thigh on top of the femur connecting the hip to the knee.

For the quadriceps, I picked the lunge and the leg extension. It’s the ultimate blend of closed chain and open chain. All of the weaknesses of the leg extension are addressed with the lunge and vice versa. Multiple studies report the lunge having nearly equal EMG amplitude of the vastus lateralis and medialis, but rectus femoris activation leaves something to be desired.

The barbell lunge outperforms the squat in VL and VM EMG amplitude, yet it’s one of the least common exercise you will see in the gym. Everyone seems to be obsessed with dumbell walking lunges, a gross replacement for the barbell variation. Firstly, the barbell lunge should be a relatively stationary activity. The participant should stand on one leg, kick the other leg back and inhibit its contribution to the activity. In reality, the activity would be better named the unilateral squat, as the rear foot/leg should play only a support or balance role: it’s a one legged squat. It’s an activity that requires the hip, knee, and ankle joints to work simultaneously. Because it’s compound, the lunge activates numerous muscle groups: the quads, glutes, adductors, calves, and low back. The barbell lunge develops the VL and VM greater than any exercise, while activating the RF to lesser degree. Considering the quadriceps muscle group makes up the most mass in the human body, it’s an important choice. The barbell lunge has the capability to be loaded progressively, it is a compound exercise, it challenges the back and abdominals, it requires upper back strength, and it challenges balance. There is an added benefit of having around 50% the weight a barbell squat would. And believe me, I’m not trying to bash the squat. I had originally chosen the squat as my first choice, but the research kept showing the lunge ahead of the squat in EMG activity. As much as I love the squat, I couldn’t deny the multiple studies all recording the lunge ahead of the squat in VM and VL amplitude.

This study conducted by Faith et. al, compared four exercises across multiple lower extremity muscle groups [12]. The researchers data shows that the lunge had the highest degree of VL and VM activity [12]. The lunge, step-up and squat are all great developers of the leg and the goal of looking at the research is to not play favorites.

My second choice for the quadriceps group is the leg extension machine. The constant tension of a machine contrasts the nature of free weights and it’s the best way to develop the RF. These two activities fit together extremely well as they supplement each other’s weakness. The leg extension doesn’t force as much VM and VL activation as the lunge, but develops the rectus femoris unlike any other activity. One study which analysed the leg extension at different knee angles found that the RF is most activated at near full extension, when the exercise is most difficult. This is likely the reason why lunge has less RF activity, considering, during the lunge, the exercise gets progressively easier as the knee nears full extension. The leg extension activity also develops the VI. Understanding VI’s location elucidates the difficulty in finding an appropriate activation, as it sits hidden underneath the rectus femoris and lies atop the femur bone. Nevertheless, some research has been conducted on the muscle [5]. It appears to be activated by the leg extension machine to a greater degree than any of the three other quadriceps muscles at a lower knee angle: 90-115, and dwindles at higher knee angles. Therefore, the leg extension machine may be considered “better” than the lunge for total quadriceps development, if you are a bodybuilder. It certainly activates all four of the quadriceps muscle (no research was found regarding barbell lunges and VI activation) in a relatively even manner, whereas doing lunges will emphasize the VM and VL. The leg extension is absolutely 100% safe for the ACL and will not make it more susceptible to injury; knee pain during the activity it is likely the patellar joint.

The data collected by Ebben et. al, compared five extremely common lower body activities [22]. The data shows the leg extension exercise having the highest peak and average RF emg activity.