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Most leg strengthening exercises stress more than legs alone, but we call them "Legs" anyway because they mostly engage lower body. Many guys neglect lower body strength in favor of chests and arms.
Cardio doesn't do it at all - runners, for example, tend not to have much leg strength. Also, distance running isn't really a cardio stress anyway - pure endurance. I used to run for miles and hike hills all day, but my legs became neither strong or powerful. Especially for women, lower body bone strength can only be maintained with resistance exercise.
For strength, (not talking about cardio or endurance here) I try to keep it simple. For functional fitness and to postpone muscle deterioration, I think all an ordinary person needs to do are five sets (with increasing reps and/or weights over time) of most or many of these basics, weekly. Some are more Calisthenics, some plain Resistance - R or C:
Barbell squats - R Squat with overhead press - R Plain squats or jumping squats - C Deadlift - R Lunges with and/or without weights in hand - C+R Step ups +/- step up and press - C Kettlebell swings - C Box jumps - C Stair machine intervals - C + cardio
Calf lifts - C, Leg press - R, and leg extensions and curls - R, are optional approaches to building up strength for the big leg efforts, but not substitutes
When you think about it, most of these exercises stress not only lower body but core too and sometimes arms and shoulders. Furthermore, they all are cardio exercises to some degree: A barbell squat routine of 5 sets will leave you gasping for a few minutes, as will just one set 15 of kettlebell swings.
I would not advise doing Deads and Barbell Squats, or any leg "R" - on the same day or more than weekly. Recovery time is needed for the big muscles. "C" lower body exertions can be done as much as you want. I tend to do calis as circuits, and Rs as dedicated efforts.
Simple resistance and flexibility workout I do every workday: take the stairs instead of the elevator to and from my 4th floor office. Up is obviously good; it's down that surprised me. Turns out it increases leg flexibility, which I noticed on my past few ski trips.
Birddog: You might look into barbell hip thrusts. Aside from the deadlifts and kettlebell swings, it looks like you put more emphasis on your quads and less on the posterior chain. And even those two exercises are not the best for focusing on the glutes. Brett Contreras is a great source on hip thrusts and other exercises that will work the back side. His web site really is quite informative: https://bretcontreras.com/ It is astonishing how much increasing your glute strength will increase your overall strength.
As an aside: You'll probably enjoy a lot of the pictures he posts, at least the ones he posted in the past, judging by what pops up here from time to time. Since getting his phd, Contreras has matured so the pinup pictures have calmed down. Your wife might like to look into his stuff, since a lot of women (myself included) are interested in building a nice backside as well as being stronger.
I do barbell squats, deadlifts, power cleans, farmers carry and for off weight days I do either burpee ladders, sprints on my exercise bike, jump rope and heavy bag work. I have done kettlebells in the past and need to reincorporate those into my routine.
I remember when I first started going to the gym when I was 18. There was a guy there who had massive arms and chest and then I noticed that he had these skinny legs. I wondered if maybe his legs just didn't get very big. I started paying attention to how he worked out. He didn't do much weight for his legs. I noticed at the gym that a lot of guys didn't do much for their legs except for the pro footballers and the power lifters. Since my main goal was to improve my athletic performance I started following what the power lifters and football players were doing. I love working my legs hard. I feel so much better over all when I have strong legs.