Tim Ferriss: CrossFit's Good, Bad and Ugly

CrossFit has taken a beating in the general health world as it's popularity has exploded onto the fitness scene in the past couple years.  People either seem to love or hate the Work Out of the Day (WOD) concept and think that the jumping, running, and olympic lifting combination can be too intense or even down right dangerous.

Tim Ferriss is a self proclaimed "body-hacker" and has written some incredible books (Check out The Four Hour Body") to improve your life and has done some great work in the health and performance world.  On his podcast, The Tim Ferriss Show, he has great interviews with top level people in each industry that provides great information.

He interviews Kelly Starrett who owns and operates San Francisco CrossFit (one of first 50 affiliates, now over 2500) and Mobility WOD.  They discuss the benefits and downfalls of CrossFit and where it has been, where it is and where it is going in the future.  This is a great discussion.  Check it out below.

CrossFit's Good, Bad and Ugly

5 Supplements You Shouldn't Train Without

I'm not sure why but it seems like supplements get a bad reputation.  I really find this odd considering how focused the world has become on "quick fixes" and making things easier.  I agree, that if you consume a well-balanced diet and eat the proper ratio of carbs/proteins/fats that you may not need supplements to the same extent as a person who eats 2 meals a day and one of them is fast-food.  However, you could still benefit from supplements.  One of the major reasons is because eating the amount of whole-food it would take to get ample amounts of some of the ingredients found in supplements would be impossible.  A convenience factor is another reason I recommend supplements.  They make it easy to eat exactly what you want, when you want even if you are on the go.

I get asked a lot what I think are the best supplements out there.  I tell people it depends what you're goals are. Are you looking to bet bigger? Stronger? Faster? Improve your 10K time?  Different goals can benefit from different supplements as they each have something to offer. In terms of brands, I'm really not too picky. I usually tell people to shop around for the good deals (i.e. gold card week at GNC or value packs at Sam's Club) as a lot of products have very similar ingredients regardless of where you purchase them as long as it's not from the guy selling protein in the alley behind the gym.  Just make sure they are a high quality brands, meaning they are certified by some form of a governing agency.

1. Protein

Protein is probably the most popular nutritional supplements used regularly by exercising individuals.  The benefits of protein are endless as each individual amino acid that makes up a complete protein has a vital role in our body.  The most popular reason to supplement with protein is probably to help build and maintain muscle mass.  This can have several positive benefits (i.e. higher daily caloric energy expenditure, increased strength & power, improved appearance etc.).  So, in conclusion if you aren't consuming enough protein from your daily diet, I highly recommend including a protein supplement into your daily stack.

2. Creatine

Creatine has repeatedly been shown to help improve performance during bouts of high-intensity exercise as well as strength and power.  Creatine helps provide energy during high-intensity exercise which allows an individual to maintain a higher force output for a longer period of time before fatigue sets in.  This could help someone train at a higher volume over time and leader to greater gains in strength and size.

See Supplements 3-5 Below

 3. Caffeine

Everyone is well aware of caffeine and what it can do for you (especially that individual who isn't a morning person and can't get out of bed without their morning java).  However, athletes are beginning to understand there maybe more to caffeine than we originally thought.  Evidence has shown that caffeine can improve short-term strength and power performance during activities such as sprinting, weightlifting and cycling.  Anyone who has ever taken a pre-workout supplement (often times loaded with caffeine) can attest to this.  Also, caffeine can help improve endurance performance by helping increase fat utilization which can spare glycogen (a major fuel source during endurance exercise) and ultimately delay the onset of fatigue.

Find Supplements 4 & 5 below:

Is Running Bad For You?!

As I'm sure a lot of you know by now, I am not the biggest fan of running. Up until now, the biggest reason was mainly because I wasn't good at it and it was painful. However, some recent research has surfaced that has given me one more reason to not like running.  A recent article published by a research cardiologist examined life-long runners and their risk of dying from heart related issues.  What he found was actually rather startling....

 

I'm sure most of you (myself included) have always believed that regularly exercise is good for you and will increase your lifespan.  On the flip side, if you sit around all day doing nothing, you probably have a higher risk of developing diseases, particularly cardiovascular disease, and therefore may not live as long.  A recent article titled: "Run for your life...at a comfortable speed and not too far" found some rather contradictory evidence that this may not be the case.  Everyone has probably heard of the individuals who have collapsed and died during/following athletic events or bouts of exercise EVEN THOUGH they were thought to have been in excellent shape.  A lot of these cases are believed to have been caused by underlying genetic conditions (i.e. hypertrophic cardiomyopathy). which is the leading causes of cardiac death in athletes.  However, there may be more to the story.

In the previously mentioned article, it stated:

"High-intensity exercise sessions lasting beyond 1–2 h cause acute volume overload of the atria and right ventricle (RV), which can bring about overstretching and micro-tears in the myocardium, as evidenced by a transient rise in cardiac biomarkers." 

Basically this is saying long-term intense exercise can actually cause damage to your heart. This kind of goes against everything we have been believing for years, right?  The authors did explain that the acute damages seen following the intense exercise does revert itself and things can go back to normal within a few days.  However, they also explained that if high-intensity or high-volumes of exercise are sustained for multiple hours a day for multiple days/months/years (i.e. marathon runners) the damage can add up and actually speed up the "aging" process of the heart!  In the graph below, it shows an individual's risk of dying, dependent on how many miles a week they run  The red bar on the far left represents a sedentary individual who has the highest risk of dying.  On the other end of the spectrum, there are 2 red bars representing people who run 20-25 miles and more than 25 miles a week and they also have a relatively high risk of dying....wait, what?A sedentary person has the same risk of dying due to disease as a life-long marathon runner who is in excellent shape!?

Continue reading below:

And On The Seventh Day...I Rested

It's that day of the week that every exercise junkie dreads....rest day.

Hi, my name is Andrew Jagim and I am an exercise addict (not me in the picture by the way).  In my eyes, if I didn't work out one day I go to bed worrying that I got a little fatter and probably lost all the muscle and strength I had worked so hard for.  I think this way even though I KNOW this couldn't be further from the truth.

A lot of people fall into the misconception that if a little bit is good, than a lot is better! This can be true for some (i.e. if you weigh 400 lbs than there is no such thing as too much time on the stair climber).  However, for those individuals who try to train/lift/workout all out, give 110%, balls out, day in and day out than you may be  hindering your potential to improve.  It may sound crazy but it's on your off-days that you actually get bigger and stronger.  if you are training at a high intensity, you are actually causing micro-tears and other cellular damage to occur within your muscles.  Just like restoring an old building, sometimes you just have to tear down the old stuff to make room for the new stuff.  In a nutshell, this is how muscle growth works.  You damage your muscles and therefore are essentially forcing to come back bigger and better than before.  So not only is your time in the gym important but so is your time away from the gym.  This is also the reason why you should try to avoid training the same body part/muscle groups on consecutive days as those muscles need proper time to recover.

Proper sleep and nutrition are not only important on training days but they may be even MORE important on your rest days.  You need to make sure you keep your protein intake up in order to support the increasd rate of protein synthesis occuring as a result of your training.  This is especially the case for the weekend warriors who during the week eat right, get a solid 8 hrs of sleep, workout every day and then when the weekend comes around they party for 48 hours, eat like crap and then expect to pick it right up where they left off on Monday.  Then refer to their weekend as their "rest days."  Not only will the extra (and worthless) calories from alcohol likely lead to increases in body fat, research has shown that alcohol can lower growth hormone and testosterone levels which are key players in muscle growth and recovery.  A lack of sleep can also hinder your recovery and can have negative effects that last several days.

One thing I should mention, is that rest days or off-days don't have to consist of 12 hrs of couch time (unless it's football season).  Your off-day can consist of light activities or even your normal exercise routine but just drop the resistance/intensity way down.  This is one thing I'll knock on Cross-fit for.  A lot of their workouts are very intense with little-to-no lower intensity or volume days which can lead to symptoms of over-training if carried out over time.  

So, moral of the story: Train hard and rest hard!

What is HMB and What Can it Do For You???

 

HMB

Hydroxy-beta-methylbuterate or HMB, is a metabolite of the branch-chain amino acid, leucine.  Leucine has been shown to have several positive effects when consumed in conjunction with a structured training program due to its anti-catabolic effects:

1.  Leucine may help increase lean muscle, strength and decrease body fat following a resistance training program.

2. Help decrease muscle soreness following intense exercise.

3. Help prevent declines in testosterone levels following intense training periods.

4. Help stimulate protein synthesis and slow down protein breakdown.


It was originally assumed that leucine was the key player in the afore-mentioned processes until the notion of HMB being involved came about in the late 90's.  When HMB is combined with a training program it appears to help aid with recovery.  Specifically it may help slow down muscle breakdown during/following intense exercise (i.e. heavy resistance training or 2-a-days).  Therefore if someone is beginning a new training program or upping the intensity, adding HMB to your daily supplement stack may help improve gains in muscle mass, strength and power over time.  It could also help an individual who is trying to cut weight, specifically fat, during a cutting phase by helping maintain lean muscle tissue even though their is a negative energy balance.  Your body does produce leucine each day however only about 5% of leucine is converted into HMB daily....so,


 "To put this into perspective, an individual would need to consume over 600 g of high quality protein to obtain the amount of leucine (60 grams) necessary to produce the typical 3 g daily dosage of HMB that is commonly used" 

                          -ISSN Position Stand on HMB




The following conclusions were released by the International Society of Sports Nutrition in a recent position stand:

1. HMB can be used to enhance recovery by attenuating exercise induced

skeletal muscle damage in trained and untrained populations. 

2. If consuming HMB, an athlete will benefit from

consuming the supplement in close proximity to their workout. 

3. HMB appears to be most effective when

consumed for 2 weeks prior to an exercise bout. 

4. Thirty-eight mg/kg of Body Mass daily of HMB (or about 3-4 g for a 200 lb individual) has been demonstrated to enhance skeletal muscle hypertrophy, strength, and power in untrained and trained populations when the
appropriate exercise prescription is utilized.

5. HMB has been demonstrated to increase Lean Body Mass and functionality in elderly and sedentary populations. 

6. HMB ingestion in conjunction with a structured exercise program may result in greater

declines in fat mass (FM). 

7. HMB's mechanisms of action include an inhibition and increase of proteolysis and

protein synthesis, respectively. 

8. Chronic consumption of HMB is safe in both young and old populations.

Wilson et al.: International Society of Sports Nutrition Position Stand: beta-hydroxy-beta-methylbutyrate (HMB). Journal of the International Society of Sports Nutrition 2013 10:6.

Cross Fit

"3....2.....1.... NEXT!!!"  These words will forever haunt my workout dreams.  For those of you who know what I'm talking about then you must have crossfitted at one time or another.  I recently attended an "Open House/Workout" at one of the local crossfit gyms in town and I thought I would share my experience.

My brother and I both played sports growing up, both workout regularly and are both in relatively good shape. So, naturally I thought to myself: "Sure I can crossfit, how hard can it be?" Stupid question. The short answer: HARD.

We arrived early, not really knowing what to expect. We eyed the people walking in, trying to gauge what kind of athletes showed up for these kind of workouts.  The people in attendance were all over the board: Some male, some female, some old, some young, some in shape...others, not. So again, we really didn't know what to expect.

As start time approached, the crossfit coaches gathered everyone around for a 5-10 minute warm up consisting of: high knees, jumping jacks, push-ups  arm swings and lunges. Okay, not bad so far, the heart's pumping, got a little sweat going, ready to go.

Next, they have everyone (~50 people) split up into groups of 4.  My group consisted of 2 male, regular crossfitters, one female who used to crossfit and myself.  Just looking around the room, I figured we had a decent shot at winning the challenge.  However, it was difficult to speculate because I didn't know what the exercise stations were going to be and what type of athlete had an advantage or disadvantage.  The crossfit coaches went over 6 different exercise stations that each group would complete once.  Each group had 3 minutes at each station and 1 person was completing the exercise at 1 time while the others recovered.  The exercises were: Stationary bike, pushups, box jumps, push press, sandbag clean/jerk, and body-weight squats.

And we're off! Our group starts will box-jumps (a good choice) and we are flying through them with a nice 20-jumps/person rhythm going. Next up: Pushups, and we do even better! My heart rate is rapidly increasing, I'm sweating, my legs and arms are already burning. With little to no rest in between stations, we move to bodyweight squats: pretty easy.  Again, we quickly move to the next station: dumbbell push-press.  With my legs burning, and shoulders aching from box jumps, squats and pushups; the push-presses were no easy picnic and we struggled towards the end. But we got through them with everyone in the group, still on their feet and encouraging each other on. Then we move to sand-bag clean & jerk swings. These are brutal... period.  The sand-bags may as well of been filled with bricks.  Our group members, are sucking air and milking their rest periods as much as they can before the person performing the exercise needs a break.  Finally, the 3 minutes are up and we move on to the final station: stationary bike. I'm thinking "Oh this will be cake, I bike all the time, I got this." And it was easy....to start with.  But the longer I stayed on the bike the more my legs seemed to be on fire and my heart felt like it was going to explode. and then "3...2....1, DONE!" And that's it. 30 minutes of non-stop circuit style stations. Instantly, I got that feeling of euphoria from my endorphins kicking in; typical after an intense workout. However, this was followed by a feeling of "Am I going to passout? Am I going to puke? I should lie down, no wait, walk it off...." Eventually I found my way to my water bottle outside and was able to walk it off a bit without collapsing in the parking lot.

All in all, it was a great workout and a good way to jump start your day. My group ended up taking 2nd, not bad for a rookie.  I've come to the conclusion that no matter how many days of lifting weights you put in a week or how many bike rides you go on...Nothing will get you ready for a crossfit workout. It's at another level.

A few apprehensions I have regarding crossfit and a few of these I have mentioned in an earlier article regarding crossfit is that sometimes they appear to lack a structured, periodized training schedule.  Meaning: sometimes more is not always better and you can't go all out day in, day out every time you workout.  Therefore, I would recommend mixing in a crossfit-style workout into your weekly routine maybe once or twice a week.  Another concern I have is the lack of back exercises.  I realize today's workout was just a snapshot of their program but other than pull-ups it's difficult to isolate the muscle groups in your back without some actual back exercise machines instead of relying solely on body weight exercises.  Regardless, it was a great workout in a fun yet challenging competition-style workout. It's a unique combination of conditioning meets resistance training.  I recommend everyone to stop by and try a crossfit near you at least once.  It's a great way to mix things up and get in a great workout.

It's The New You

It's a New Year, so why not make it a New You.  Everyone always talks about their New Year's resolutions and how this is going to be the year that everything changes, the year you follow your diet and fitness plan religiously, the year you finally hit your goals, the year.....

Regardless of what your goals are, if they have anything to do with your body, nutrition will play a major part. And the biggest questions is: How much should you be eating?

Your daily nutritional needs are determined by a variety of factors such as gender, age, body size (specifically muscle mass) and activity levels.  There are several ways to estimate the amount of energy or calories your body needs to support it's basic metabolic functions or your basal metabolic rate.  For simplicity's sake here is a general rule of thumb for how much you should be eating:

On days that you are working out, you should consume ~18 calories per pound of body weight if you are looking to maintain your body weight.

If you are looking to add weight (hopefully just muscle mass but you never know) you should consume a little  bit more and strive for ~20 calories per pound of body weight on days that you are exercising (3,000 calories per day for a 150 lb person) and 18 calories per pound on rest days.

For individuals looking to gain/maintain muscle and lose fat at the same time (never easy to do) you should be in the range of 18 calories per pound on workout days and 14-16 on off days.

*Another key concept to remember, is what type of calorie you are consuming. If I had to pick the most important macronutrient, I would have to say protein.  Protein is involved in protein synthesis which helps you maintain and build muscle mass and muscle mass is highly correlated to calories burned throughout the day.  Focus on hitting your daily protein goals first and then fill in the rest.  For a general rule of thumb, I would shoot for 1 g of protein per pound of body weight followed by 1.5 g of carbs per pound of body weight.

Remember, these are just general numbers to shoot for. Don't freak out if you go over or under by a little bit each day as your body will adjust.  Also, be patient; changes in body composition do not occur overnight.

Personalize Your Workouts

Every person is different, everyone's anatomy and physiology are different, everyone's goals are different...  All reasons why everyone's workouts should be different also!!!  This message is not only important for people hitting the gym every day but also for the trainers, coaches, PT's or whomever is prescribing the program in the first place.  I have to admit, in my early years of personal training I was lacking this blatantly obvious concept in my program design.  I was guilty of writing programs for my clients that were similar to ones that I myself used in my own workouts and enjoyed doing until I realized that my 45 yr old female client probably didn't care if she had huge traps or could bench press 300 lbs. Therefore the theme for today is specificity!

 

 This concept of specificity is important to realize as your are planning your exercise routine so that your program is specific to you and only you.  It's not always as easy as cutting a routine out of a Muscle & Fitness magazine, following it and then hoping to look like the guy on the cover in 12 weeks.  I often get asked to write a quick program for someone and send it to them without every seeing them in a gym before.  I try to explain to people that it may not be the best program for them because I don't know what kind of experience they have with some of the exercises, whether or not they can physically do them and/or if the gym they workout at even has the required equipment.  Also, not all people call exercises by the same name, (some exercises don't even have name!) so it's tough to explain the exercises without physically being present to demonstrate them and make sure they are done properly.

Each person is different and responds differently to exercise.  For example a 20 yr old can handle a relatively high training load and can workout/train multiple hours a day 5-7 days a week whereas a 70 yr old may need days in between workout sessions in order to recover.  Furthermore, some people may not be able to perform certain exercises whether it be from an old injury, lack of coordination, or they're 7 ft tall and a back squat is completely out of the picture.  Therefore it's necessary to modify workouts so that they not only fit your individual bodies but your goals as well.

 

 Another concept of specificity is training for a purpose or a specific goal.  A football player doesn't need to be running 80 miles a week just like a swimmer doesn't need to be doing a bunch of jump squats to improve their vertical.  Similarly, in terms of fitness goals, if you are looking to lose weight you don't need to be doing 5 sets of 3 reps with 5 minutes in between sets in the weight room, or if you are trying to increase strength and size you don't need to be doing a back squat.... on top of a stability ball.... on one leg....underwater for sets of 100.

How To Do This?

 So, now the important question: How the hell do I do this?  Well, below are a few tips on how to design a workout specific to you!

1. Set Personal Goals

Before you start any type of program you need to decide what you want to get out of it. Do you want to lose weight? Build muscle? Improve your endurance? Or just look good in a swimsuit? Regardless of what you want, write it down, set a timeline (a realistic one), join a gym and go for it.  In life you often hear the phrase "more is better" is this case it's not always true.  I'm all for the idea of you wanting to be awesome at everything but some times it's simpler to just pick 1 or 2 goals and focus solely on them because a lot of times if you have too many goals they can get in the way of each other and become conflicting.  For example, it's difficult to try and improve your marathon time while trying to gain 40 lbs at the same time. 

2. Know Your Environment

Know what you have to work with; meaning if your goal is to improve your swim performance but you don't have access to a pool, you may not hit your goal as quickly as you'd like to.  The same goes for weight lifting or gym workouts.  If you belong to a smaller gym that doesn't have a lot of equipment or machines, you need to get creative and design a workout that focuses more on body weight exercises or unconventional exercises such as "playground pullups" or "tire flips."  The creator of P90X has made a fortune off of this concept.  He has designed a plethora of workouts that you can accomplish all in the confines of your own home.

3. Trial/Error

Don't be discouraged when something doesn't work or goes wrong. For example, if you wanted to increase your back squat but you soon realize you can't properly hold the bar behind your head because of shoulder issues, don't just quit, try something else; maybe incorporate front squats or leg press into your routine instead. It's important to constantly try new things and plug them into your workouts because variety is the spice of life and it will force your body to continually adapt and improve.  It's also just as important to toss something out if it's not working for you or has gotten too easy.  Keep your body guessing!

4. Monitor Progress

In order measure the effectiveness of your program and determine how close you are to achieving your goals, it's important to monitor your progress throughout the way. This can mean anything really, depending on what your goals are. If you were trying to gain lean muscle, you can have your body composition assessed. If your goal was to improve your 5K time, what better way to monitor your progress than to go out an run one!? If you are working towards strength/power goals, you can test your 1RM on certain exercises (this is especially important for program design as you continually need to adjust your weights each week as you get stronger).

5. Continually Improve

This tip goes along with the previous two.  In order to improve, in whatever area it may be, you need to continually challenge yourself so your body adapts.  Without progressively overloading your system you will hit plateaus and become stale and you will never reach your goals.  So go big or go home!

 

No One Ever Got Awesome Just Sitting Around

How To Spice Up Your Workout

Often times workout routines become a chore, a routine, just something you check of your daily to-do list. And that's fine for a lot of people and it's definitely better than what the majority of Americans do everyday. However, the best way to improve i.e. get bigger, stronger, faster, is to change your routines and make your body adapt and force it to make improvements.

The easiest way to do this is make adjustments to your daily workout routine. This can be as simple as switching up your daily splits and hitting different body parts different days or completely overhauling your entire workout by incorporating different exercises, set/rep schemes, recovery periods etc.  I typically recommend to completely change your workout routine at least every 3-4 months, if not more.  I understand how easy it is to get to the gym, hit your favorites, do what's comfortable and get out of there but that's all it is, is easy. You're not getting the as much bang for your buck as you could. So, don't let all of that time and work go to waste. Change up that workout and mix things up a little bit.

Below are some modifications/lifting techniques that you can incorporate in to your workouts to mix things up a little bit and add some intensity to your workouts:

1.  Drop Sets
The term "Drop Sets" refers to a weightlifting technique used following your last set of a particular exercise.  Follow your last rep of a set, or when you've reached failure, you immediately drop the weight ~20-40% and continue to lift the new weight as many times as you can.  This technique is a good way to overload your muscle fibers and stimulate muscle growth.

Warning: They call them drop sets because you drop the weight on your last set, not because you drop the weights on your face. It's recommended that you use a spotter for these sets as your arms, legs or whatever are going to feel like jello when you're done.

2.  Super Sets

Super sets is a technique that combines two exercises into one never-ending set. For example, if you were super-setting bench press with lat pull-downs, as soon as you finished your last repetition of bench press you would immediately head over to lat pull-downs and complete a set followed by a rest period.  Then you will start over with bench  press at the end of the rest period.  Some people, will use 2 exercises that utilize opposing muscle groups similar to the super set mentioned above, whereas others will super set similar exercises i.e. back squat with leg press.  Super sets are a good way to speed up your workouts and keep your heart rate elevated.

3.  Negatives
Negatives or "forced reps" are techniques used by weigh lifters to promote muscle growth and strength by lifting heavier weights than you normally can handle. How is this possible?  During a muscle contraction there is a concentric (shortening) and eccentric (lengthening) motion.  During the eccentric motion, a muscle can handle heavier loads than during a concentric motion. For example, during the bench press the lowering motion is eccentric and the pushing phase is concentric.  So, in order to apply this technique you should lift a weight that is 10-20% heavier than you normally would for that rep range and with the assistance of a spotter, focus on the eccentric motion of the exercise.  In other words, you should be doing the lifting during the lowering phase and then with the help of your spotter, get the bar back up to the starting position and then repeat.  This is a very effective strategy to not only increase muscle strength but size as well because heavy eccentric lifting is a powerful stimulator for muscle growth.  However, I recommend only doing negatives once every 6-8 weeks as eccentric lifting can be damaging to the muscles and your body needs time to recover.

 

4.  Cluster Sets
Cluster sets, inter-repetition rest, rest-pause are all names for a lifting technique that focuses on repetitions separated by short rest periods to allow for fully-recovered explosive movements.  By allowing your muscles to recover in between reps, you should be able to lift heavier loads and heavier loads, equals greater strength gains.  Below is a comparison between traditional strength training and cluster sets:

Traditional Strength Training:
  -  6 sets of 6 reps with 3 minutes of rest in between set @ 80% of your 1RM typically taking ~20ish minutes to complete.

Cluster Set Training:
  -  (1+1+1+1+1+1)*6 sets.  In the scenario, each plus sign corresponds to a 10 second rest period.  So, during 1 set, you will complete six reps with 10 sec of brief rest in between each rep.  Then, following your 6th rep you will rest for 3 minutes.  This will take approximately the same amount of time ~20-25 minutes but you should be able to use a heavier load of roughly 85-90% of your 1RM.

5.  Circuit
A circuit style routine is very common in the fitness industry.  During a circuit, you will continually move from one exercise to another without rest until the very end.  Each "circuit" or rotation through all of the exercises is one set.  Usually people will do 2-3 sets per workout.  The idea is to move as quickly as possible and keep your heart rate elevated.  Some people recommend doing sets with a certain number of repetitions i.e. 15 reps for each exercise.  Another technique is to complete as many repetitions as possible for a certain time period i.e. 30 seconds per station.  Circuit style workouts are a great way to combine your weight lifting with your cardio as you are continuously moving from one exercise to the next forcing your body to ramp up the cardiovascular system while also stimulating your muscles to grow.  It's also a way to get a quick, efficient workout in as most circuits usually only last 20-40 minutes.

6.  1-Arm/Leg Exercises
If you can do it with 2 legs, try it with 1! One-legged, or "armed" exercises are a great way to mix things up in the weight room, especially if you have any muscle imbalances.  Obviously you won't be able to lift as much weight as you could with 2 limbs, but this way you are forcing one limb to do all of the work instead of having one overcompensate for the other (if there are imbalances).  Also, one-limbed exercises will engage the core to a greater extent as your body will be forced to stabilize itself due to the odd positioning and alterations in your center of gravity.  In terms of what exercises you can do, the sky is really the limit. I've seen 1-leg squats, leg press, dead-lift, leg curl... Similarly for upper body exercises, I've seen 1-arm lat pull downs, bench press, rows, etc.