The human body is pretty simple.

Each muscle has its set functions. Occasionally movements are innovated or popularized but for the most part nothing is new. For example:

The biceps flexes at the elbow and supinates the forearm.

The lattissimus dorsi adducts, extends, and internally rotates the arm.

The gastrocnemius flexes the knee and plantar flexes the foot

You get the idea. These things aren't changing.

Workouts would get boring pretty quick if this were the case

Luckily there are a ton of different ways we can vary exercises and movements. We can make it harder or easier or change the purpose of the same exercise from fat loss to muscle gain or even power development with a couple simple tweaks.

You have a responsibility to your clients to know and understand at least 2 progressions and regressions of every exercise you teach.

You must know when and where to apply the different training variables I've listed below.

It's irresponsible for a trainer to give every one of their clients the same exact exercises. However I also believe that trainers can and should template their workouts and give each one of their clients with similar goals the same workout.

The difference is in how they apply the variables.

How to Progress and Regress an Exercise

1. Lever length - Understanding some basic biomechanical principles helps you easily make any exercise harder or easier. If you want to make an exercise harder move the weight farther away from the fulcrum. If you want to make it easier simply do the opposite.

Take the plank as an example. A basic plank is pretty easy but lifting one arm and placing it either in front or stretched out beside the body increases the intensity of the exercise.

2. Balance - This one is more obvious. The more balanced your client is the stronger they will be. Knocking them off balance increases the challenge of the exercise.

This comes with a warning -- always keep the clients goal as the #1 priority. A squat on a bosu ball makes the exercise harder but it isn't going to make the client strong. Instead it's going to make the client better at squatting on a bosu ball. When introducing balance as a variable make sure it doesn't take away from your clients primary goal.

3. Close your eyes - This one popped up on the Facebook thread. I can't say that I've ever told a client to close their eyes in order to make the exercise harder but I can imagine it would. I would think that this would be an effective technique if your client is having a hard time feeling the movement. Not sure I would suggest it for anything else though.

4. Manipulate reps - One of the more common techniques. Certain exercises can have their reps manipulated more than others.

You would have a hard time performing the lateral raise, for example, in the low rep zone. The movement doesn't allow for heavy loads to be lifted explosively.

The squat is a perfect example because it can be used for any goal with a change in reps. Train in the 1-5ish rep zone and you're developing power. 6-10 rep squats are great for muscle development. Anything higher and you build muscle endurance and take advantage of the large muscles being worked for fat loss.

5. Time under tension (TUT) - This is my favorite variable. TUT is ignored far too often. The nomenclature for each phase of the lift is eccentric - pause - concentric - pause (all in seconds). So a lift with a 41X0 tempo would call for a 4s eccentric - a 1s pause - an explosive concentric - no pause at the top.

You can manipulate TUT to fit any clients goal. It's also a great tool to "wow" a client early on in training because few trainees pay close enough attention to it. This brings a whole new element to their workouts that they previously tried to rush through.

The general rule is that the longer time under tension the more muscle damage and therefore muscle development. A breaking point does exist somewhere around a 45s - 1 min set (although this varies).

Strength generally calls for an explosive concentric contraction and a controlled or non-existent eccentric (the weight is dropped as per a competition deadlift). For fat loss clients I liked to employ 2010 tempos. Here the client performed the exercise under control but was able to maintain a good pace.

6. Weight - If it's heavy it's hard. If it's light, don't waste your time.

7. Shape of implement - While not commercially available odd-shaped implements are fun to lift and can add in a new dimension to training. Sandbags achieve this because the weight isn't distributed evenly.

Perhaps the most common example today is the kettlebell. Because the weight distribution isn't uniform (the weight is concentrated at the end) the bell generates more inertia farther away from the body. This forces the client to engage harder in order to control it.

I also love slosh pipes and built a couple for park workouts. I simply went to home depot and bought a couple PVC pipes, filled them to different weights with water, and capped them on the end. Try doing a squat holding a pipe with water sloshing back and forth -- talk about a core challenge.

8. Stance - Despite popular belief the only way to stand when performing an exercise is not shoulder width apart with soft knees. Stance, when manipulated properly, is a powerful variable that can jump start your clients program. Here are my favorite variations:

• Split stance - This is a good stance because it is generally easier on the back and allows the client to maintain a strong posture. The wider the split the more balanced the client will be. Just make sure to change up the leading leg so they get the oblique benefit on both sides.
• Kneeling -Want to have your client do a shoulder press or biceps curls but give them a great ab workout at the same time. Have them kneel while performing the exercise. The weight will have to go way down.
• Half-kneeling - An in between between standing and kneeling. There's a great core benefit here and the glutes on the side of the resting leg will fire as well.
• Wide stance - A wide stance makes it easy for the client to balance. It also gives the adductors a nice stretch. probably not advantageous for most clients but a nice change of pace from time to time.
• Feet close together - The closer the feet are together the harder the core challenge. Depending on the exercise it could be advantageous or not. I like manipulating this variable  for exercises that center in on core stability like the paloff press.

8. Eccentrics (negatives) - A negative is a very slow controlled contraction causing a lot of muscle damage. These should only be used for advanced trainees and definitely under sets of 5 (probably even under 3 reps). A negative usually lasts around 10s and a spotter assists the lifter in the concentric portion of the lift. These will make you very very sore the next day.

9. Rest time - Rest is another one of those variables that isn't used properly often enough. Most trainers learn about rest periods and when to use each one when they write their exam and then largely forget about it in practice.

0-45s rest builds endurance.

45s - 1.5mins builds muscle.

1.5mins+ is for strength training.

10. Loading schemes - Every exercise in a workout is directly affected by the preceding exercises. Loading schemes can add or decrease intensity of a workout or on a particular muscle group. There are too many to list here. Two examples are:

Pre-fatigue - This is when an exercise is performed that exhausts a single muscle group immediately followed by a multi-joint exercise using that muscle. This can be dangerous if the lifter isn't experienced. For example I wouldn't perform hamstring curls before a deadlift unless the lifter has a couple years of lifting experience.

Post-fatigue - This is when a multi-joint exercise is followed immediately by a single joint movement that uses one of the main muscles of the multi-joint movement. For example a deadlift followed by a hamstring curl would be considered post-fatigue. I used this loading scheme often when ramping up intensity and volume in my programming.

11. Pauses - Pausing could be incorporated into the earlier discussion on tempo but I decided to give it it's own category. Momentum is a powerful way to generate force but sometimes it's not warranted. I found that new clients had a propensity to use momentum too much, so I forced them to pause at the end of each rep and start over.

In terms of application to training a full pause before a concentric contraction can train a client to recruit larger motor units faster. If you're looking for power generation that's a good thing. I also found it effective for elderly clients in helping them recover from trips to avoid falling. I didn't need them to generate more force more often, instead I needed them generate force quicker for one rep.

Pausing at different stages of the contraction can also increase the intensity by increasing TUT and forcing the muscle to work at weaker ranges for longer periods of time.

Here's a video of my friend Ben Bruno performing triple pause pull-ups:

12. Range of motion (ROM) - We're taught to perform full ROM movements all the time and, for the most part, that's true. There are times when cheat techniques of semi-reps are warranted as long as they're performed safely. I always said, "if the choice is to get 0% because you cannot perform a full rep or get 30% and perform a partial rep. I would choose the 30%".

If the client is already proficient in proper form partial reps can add more intensity into the movement. Especially on arm day. You know, for the pump.

13. Grip - I left grip to the end because of how strongly I believe every trainer should master it. Different grips force the body into different positions. Add to that the different motor recruitment that can happen and change in muscles used and it's a powerful tool

The main grips on a couple large exercises are as follows (by no means a conclusive list. Add more in the comments below please).

Chin up: Wide pronated, close neutral, wide neutral, close supinated.

Squat: High bar, Low bar, close overhand, wide overhand.

Deadlift: Barbell (BB) two-hand pronated, BB mixed (be careful of biceps tears), BB overhead, Dumbbell (DB) goblet, 2 DB by the side, 2DB on shoulders.

Bench press: BB Close grip pronated, BB wide grip pronated, BB medium grip supinated, DB neutral grip, DB pronated, all different inclines (DB or BB)

Fat Gripz: The thickness of the grip also has a major effect. Thicker grips change the activation pattern. Not only do they increase the grip challenge (something a lot of clients need) but they also tend to help people "pack" their shoulders. I found them useful in training weekend warriors in that it kept them safe during pressing movements.