High Intensity Interval Training or HIIT is training where you alternate between intervals of high-intensity and low-intensity exercise. An example would be sprinting all-out for 100 meters then walking for 100 meters then repeating. One cannot sprint at full intensity for a prolonged time because sprinting and any other form of high-intensity cardio utilizes the anaerobic energy systems, specifically the Phosphocreatine system, which power short-term activity. After going all out, one must rest and give the Phosphocreatine system time to “recharge”. Additionally after sprinting all-out a couple times you are going to start feeling fatigued. After 10 sprints you are pretty much worn out. While you might not be able to sprint at full speed anymore you can still walk and jog as the intensity is not as high as sprinting and other uses the aerobic energy systems.
But women in particular are neglecting strength training at their own peril. It’s the only kind of exercise that makes muscles bigger, which lets them generate more strength and force, faster. “Muscle mass allows us to move,” Tucker says. Young people tend to take for granted the day-to-day parts of life that require strength, like walking up stairs or picking up a baby. “But a sedentary lifestyle means that people are gradually becoming weaker over time,” he says. Building muscle can fight back against that process.
Second, women may recover from training a bit faster than men (one, two, three).  When I’ve mentioned this in the past, the counterargument I typically hear is that women don’t create as much force, so of course their muscles won’t sustain as much damage, and will therefore recover faster.  However, that doesn’t make much sense when you think about it. For starters, I’m not aware of any evidence showing that people who are stronger or more muscular at baseline experience more muscle damage, more soreness, or larger/longer performance decrements than people who are weaker or less muscular, all else being equal.  More importantly, what each of your muscle fibers “feel” is the tension on that specific fiber; the contractile force of the entire muscle shouldn’t matter, as long as each fiber is being recruited to a similar degree and experiencing a similar amount of tension. I think the more likely explanation is that estrogen may exert a protective effect on muscle, limiting damage and potentially accelerating repair.
Keeping your right arm fully straight and your core tight, lift your left hand from the ground and touch your right shoulder. Return to pushup position, then repeat the motion on the other side. Focus on keeping your hips square with the ground as you do each tap. Do 4 sets. Work for 40 seconds then rest for 20 seconds during each set for Week 1. During Week 2, work for 50 seconds, the rest for 10 seconds.
Though BeFit is another company that provides the majority of it’s content via paid downloads, subscription services and DVDs, it can still be a great resource for free, at-home workouts. It boasts a plethora of videos in the 10 to 20-minute range, done by top fitness trainers like Denise Austin, Jane Fonda and Scott Herman, to name a few. While this channel is perfect for those who want to raise their heart rate in a shorter amount of time, there are a handful of longer videos sprinkled throughout the lineup for those with more time available. Unlike a few in this list, this channel is definitely not aimed specifically at women and has many workouts that would be suitable for men looking for a challenge.
You should follow this up during your workout by sipping 2-3 servings of Xtend throughout your entire workout. This will ensure protein synthesis levels stay elevated and your body is primed for growth. While many people overlook the power of workout nutrition, with the Scivation Workout Nutrition Stack you can be ensured that your body has the nutrients and substrates it needs to performance better than ever and gain the lean muscle you never could before while supporting fat loss.
Sit with both feet about hip-width apart on the ground, feet flat on the floor. Your shoulder blades should be against a bench, arms wide for stability. Lift your right foot off the ground, raising it as high as you can and bending your knee. This is the start. Now brace your core, and use your left glute to press your entire torso off the ground, driving your torso and left thigh so they’re parallel to the ground. Pause here, then return to the start. That’s 1 rep; do 2 sets per leg.
The narrowing of the gap as competitiveness increases suggests that women may truly continue gaining strength at a slightly faster relative rate across their training careers.  Similarly, a 2014 study of elite athletes in a variety of sports found that the women had about 85% as much lean body mass as men; before training, women tend to have ~60-70% as much lean body mass as men, suggesting that women may actually gain relatively more muscle than men long-term (though, for all of these comparisons, you can’t assume causation from cross-sectional analyses).  
When you strength train, your muscles are broken down, and then rebuilt over the next 24-48 hours. While your body is rebuilding those muscles, it’s recruiting more calories and energy to make the process happen (generally referred to as the ‘afterburn’ effect).  What this means is that your metabolism operates at a faster level even while you’re sitting on the couch after a workout.