There's a lot of science supporting blood flow restriction (BFR) training. It consists of attaching a compressive cuff or bands around your limbs, then doing isolation exercises for those limbs.

If you don't have access to heavy equipment, BFR allows you to still get an effective muscle-building workout. It also makes bodyweight and light exercises less boring by dramatically reducing the number of reps needed before you hit failure. You might only need 12-15 bodyweight squats instead of 40. BFR should be done to failure or close to it for best results, especially for hypertrophy.

Note: Use the proper equipment. A dedicated BFR kit will give you better results and be safer than just putting a tight knee wrap around your arm or leg. The amount of compression is important. Too little, and you don't get the full effect. Too much can be dangerous for your cardiovascular system. A proper pressure for arms is between 100-220 mmHg. For legs, it's 150-250 mmHg.

A decent BFR system (like this one) comes with a pressure gauge. You can even use pressure increase, instead of weight increase, as a progression method.

Training with lighter weights using BFR leads to similar muscle growth as training with heavier weights. In fact, a study looked at the impact of BFR on sprint training, and the same thing was found: BFR made submaximal (easier) sprinting a lot more effective at improving speed (1).

How does BFR do that? Originally, the science pointed toward an increase in local growth factors (IGF-1, MGF) (2). But recently, researchers found that the deprivation of oxygen to the muscles (because blood is stopped from coming in or out) leads to an increase in the recruitment of fast-twitch muscle fibers and a decrease in the recruitment of slow-twitch muscle fibers.

The fact that slow-twitch fibers are more reliant on oxygen likely explains it (3). But as you know, fast-twitch fibers have much greater growth potential. If you can recruit them more easily, you'll likely promote more muscle growth or even power/speed.

Loaded stretching is one of the most underrated methods you can do.

Basically, just hold the stretched position of an exercise under load. That load can be barbells, dumbbells, or even your own body weight. Simply lower the weight until you reach a position where the target muscles are stretched. Hold it by contracting the muscles hard when you reach that position, so it becomes an isometric contraction. Actively try to pull/push yourself down even more.

You'll slowly reach a position that's more and more stretched. It becomes a very slow, very gradual eccentric or negative action as you go deeper. As fatigue sets in, you won't have the strength to hold the position any longer.

It's not just a stretch; it's contracting a muscle at its most lengthened state. This means using added weight or your body weight to force the target muscle to contract. Along with a rapid increase in mobility, benefits include:

• Stimulating Muscle Growth: Loaded stretching causes an occlusion effect similar to BFR: stretching and muscle contraction both contribute to reducing blood entering and exiting the muscles. You get the same benefits as BFR when it comes to growth factors, lactate accumulation, and increased fast-twitch fiber recruitment. All of this can lead to growth.
• Increased IGF-1 Receptor Sensitivity: This is another element that allows you to stimulate growth from loaded stretching or make other portions of your training more effective. For example, do loaded stretching and BFR dynamic exercises in the same session.
• Better Contraction When the Muscle is Lengthened: Muscles produce less tension when they're lengthened. As a result, you're more reliant on the stretch reflex to produce force and are more at risk of injuries. But loaded stretching can program the neuromuscular system to produce more voluntary force from muscle contraction in that position. This will make you stronger, less likely to get injured, and more likely to build muscle from traditional exercises.
• Strengthened Tendons: Loaded stretching builds thicker, stronger tendons. By itself, this is worth it. It makes you less likely to get injured, increases strength, and can even improve power.

Try accumulating 3 minutes under tension. You won't need a lot of external loading. You can do sets of a specific duration: 3 x 60 seconds or 2 x 90 seconds. Or you can shoot for getting 3 minutes continuously with short breaks – just long enough to take 3-4 deep breaths.

Split squats, push-ups (hands on blocks), and dips work well with this method. If you have light dumbbells, you can do all sorts of exercises.

These methods are associated with improvements in jumping and sprinting capacity, as well as agility. But are they worth doing if your goal is to get bigger and maybe stronger? I believe they are.

1. Plyometric training increases muscle contraction strength in all three types of contractions (isometric, eccentric, and concentric) due to increased muscle activation (4).
2. Plyometric training leads to the conversion of slow-twitch fibers to fast-twitch fibers. Having more fast-twitch fibers will increase your strength and muscle growth potential (5).

If you don't have access to heavy weights, then jumps and plyos can be useful. You can easily maintain (or even increase) muscle mass. But, maintaining or improving strength is much harder. In part because you get less comfortable handling heavier loads, but also because you lose neuromuscular adaptations. You might maintain muscle mass, but you lose the capacity to send an excitatory drive that leads to high force production.

Doing explosive work has a strong neurological effect and can help you maintain and improve your neuromuscular capacities. While you'll still need to regain the "feeling" for handling heavy weights, you'll still have the muscle mass and neurological efficiency necessary to produce a high level of force, so your strength will come back quickly.

Let's look at the difference between the three methods:

Jumps: All the methods mentioned in this section can be considered jumps. But in this classification, the jump category refers to the lowest impact movement: jumping with a reset after every rep. Basically, you jump up, forward, sideways, or behind, but when you land, you reset and take a few seconds before the next jump.

Doing jumps that aren't back-to-back (jumping as soon as you land) takes out the complex and demanding action of using kinetic energy to convert it to potential energy, creating maximum stiffness and the greatest stretch reflex possible to produce more power or speed in the next jump. Start with regular jumps before moving to the more demanding methods.

Plyometrics: When your body "falls" down from a jump and your feet contact the floor, you accumulate potential energy and activate the stretch reflex more so than if you just dip down to jump. This can increase the power of the jump and the speed at which you're jumping.

The more muscle and tendon stiffness you can create upon landing, the more power you'll have. This means if your heels strike the floor upon landing, you're not going to get maximum results. Your heels need to land as close to the floor as possible without touching it.

Plyometric exercises are when you "link" several jumps together by jumping as soon as you land. There are two main levels of plyometrics: low and high intensity. Low-intensity plyometrics refers to simple bounding drills where you're not aiming to produce maximum height (or distance).

High-intensity plyometrics refers to exercises where you're trying to produce maximum height or distance on every jump. The higher you go, the greater the force upon landing. If you're well-trained in producing stiffness, this greater landing force will create an overload which will increase power and speed.

Shock Training: This method includes both depth jumps and altitude drops. In both cases, you stand on a box as relaxed as possible, then step off of the box. You must step off, not jump off, because you need to stay as loose as possible. You then land on the floor with various levels of knee bend.

The landing must be both soft (it shouldn't make any noise) and stiff (you must be able to stop any downward movement as soon as you land).

In the depth jump, you'd then proceed to jump up as high as you can. This works by creating even more force upon landing than normal plyometric exercises. This will lead to more power and even strength gains, provided your body is ready for it.

The recommended box height for depth jumping is between 75 centimeters (30 inches) and 1 meter (40 inches), but this might be too high for some. A few inches higher than your maximum vertical jump is a good place to start. For example, if your max vertical jump is 25 inches, go with a box around 28 inches.

For altitude drops, go a bit higher, around 8-12 inches higher than your max vertical jump.

When it comes to jumps, plyometrics, and shock training, do sets of anywhere from 3 to 10 reps. I like sets of 5.

"Isometric" means producing force without changing the length of the muscles with movement. The two main categories are overcoming and yielding isometrics.

In overcoming isometrics, you're trying to push or pull against an immovable object. Typically, the recommendation is to push as hard as possible for the duration prescribed.

In yielding isometrics, you're holding an object at a fixed joint angle. The object isn't immovable, so this is a submaximal/longer duration method.

While they're not as effective as traditional training, don't dismiss the value of isometrics. You can use isometrics for two main purposes:

Isometrics for Muscle Mass: Use sets lasting 40-90 seconds. Why that long? Because they don't provide the same mechanical loading mechanism (stretching muscle fibers while they're producing force), so you need to rely on another mechanism to stimulate growth. That mechanism is the accumulation of local growth factors and lactate, which are maximized during intense efforts for 40-90 seconds.

By their nature, yielding isometrics are better suited for longer-duration work. You can also use overcoming isometrics, but it becomes more challenging to select the proper contraction intensity. If you push as hard as humanly possible, you'll hit the wall after 12-20 seconds. And if you don't go hard enough, you might be wasting your time.

Essentially, you want to reach a point that could qualify as "muscle failure" in the 40-90 second window.

Isometrics for Strength: Here, you need a very intense effort. As such, overcoming isometrics are the better option. Push or pull as hard as humanly possible against the immovable object for 6-12 seconds. This works mostly by maintaining or improving neuromuscular function. When you get back to the gym, you'll still have to get used to moving heavy weights, but the resources you'll need will still be there.

If you've been paying attention, you know that:

1. The best way to maintain or improve muscle mass is to use BFR and longer-duration isometrics.
2. If you want to maintain neuromuscular function, use jumps/plyometrics/shock training and short-duration isometrics.

If you want to use both approaches to improve both your muscle mass and neuromuscular functions, do so on different days: neuromuscular days and muscular days.

One tool that I like for overcoming isometrics is called the Isochain, sold by Dragon Door.

The Isochain has a built-in sensor that tells you how much force you produced during your set, both the peak and average.

EMS is obviously not the first thing to look at, but it's an interesting topic that some training geeks will appreciate.

This is a pricier recommendation, and for the price you could probably get a barbell and weights, and it'd be a better choice. But if you don't have the space to lift weights at home, EMS can be a valuable tool even when you get back to regular training. I use it as a supplement to my training for building strength, correcting a lagging muscle, helping with recovery, and for training while injured.

Years ago, I used it to bring my squat up. I had a rudimentary device and didn't know what I was doing, but it still worked. My squat and front squat improved by a good 30 pounds in a fairly short period of time. I eventually got better units that have pre-planned programs for various training goals. I've been using Compex units since 2007.

I don't use them all the time. EMS works for 10-15 sessions for a muscle, after which it loses its effectiveness. It's best to use it in blocks of a few weeks. I use it early in a preparation cycle where I focus on strength or when traveling for seminars.

EMS isn't a cure-all, but it does have some interesting benefits:

It favors the development of fast-twitch fibers and makes them more sensitive to recruitment. More recruitment may mean an increased ratio of fast-twitch fibers. Plus, when used with the proper intensity, wave type, and work-to-rest ratio, it can significantly increase strength, power, and speed.

Other modes can facilitate recovery after a hard session. It can be used to prevent detraining when you can't train. And it can allow you to reduce the volume of strength training during certain periods, substitute it with EMS, and still get a similar progression while recovering and working on other types of training like speed, agility, or sport practices.

Here are some guidelines for proper EMS use:

• Get a quality unit. The gadgets sold on TV to "build your abs" don't provide the proper waveform, contraction/relaxation ratio, or intensity level to actually work.
• Intensity is king. You need to use the highest tolerable level of intensity during the tetanic contraction periods. Some studies showing poor results with EMS likely used insufficient intensity. If it's adjusted by the researcher, it's hard to know how close you are to a subject's limit tolerance. And if it's self-adjusted, the intensity can depend on the pain tolerance of the subject.
• Pay attention to timing. EMS works to increase strength for 10-15 sessions per muscle. After that, the effects are limited.
• Plan treatments accordingly. You could either rotate muscle(s) every 10 treatments (3 weeks or so) or use EMS only in blocks of 3-4 weeks (10-12 treatments). Just insert them once per training cycle (12-16 weeks) when strength gains are the primary objective.
• Strategize your sessions. For developing strength, do it either at the end of a workout, as a secondary workout a few hours after the main one, on different days than lifting, or instead of a lifting workout. I use EMS as a secondary session on the lifting day.
• Keep soreness in mind. The proper intensity level will cause plenty of muscle damage and can leave you sore for a day or two, especially after the first 3-4 treatments. This is why I prefer to do it on the same days as lifting.

1. Behringer, M. et al. Low-Intensity Sprint Training With Blood Flow Restriction Improves 100-m Dash, Journal of Strength and Conditioning Research: September 2017 - Volume 31 - Issue 9 - p 2462-2472 doi: 10.1519
2. T. Abe, T. et al. Skeletal muscle size and circulating IGF-1 are increased after two weeks of twice daily "KAATSU" resistance training, International Journal of KAATSU Training Research, 2005, Volume 1, Issue 1, Pages 6-12, Released July 18, 2008, Online ISSN 1882-6628, Print ISSN 1349-4562
3. Krustrup, P. et al. (2009), Heterogeneous recruitment of quadriceps muscle portions and fibre types during moderate intensity knee-extensor exercise: effect of thigh occlusion. Scandinavian Journal of Medicine & Science in Sports, 19: 576-584
4. Behrens M. et al. Plyometric training improves voluntary activation and strength during isometric, concentric and eccentric contractions, Journal of Science and Medicine in Sport, 2016, 19:2, 170-176
5. Malisoux L. et al. Stretch-shortening cycle exercises: an effective training paradigm to enhance power output of human single muscle fibers Journal of Applied Physiology 2006 100:3, 771779