Fitro Dyne Basic
FITRO DYNE - BASIC VERSION
In weight exercise, the muscles lift a mass m by applying a force F (equal to m.g) at velocity v producing power P (equal to F.v). In current practice in strength training, attention is largely directed to the weight itself, whereas velocity and power are usually neglected. However, these parameters may be of great importance, not only for weight training, but for the assessment of strength capabilities. FiTRODYNE represents simple easy to use system to be used for the registration of velocity and power in concentric phase of weight exercise.
Principle
The FiTROdyne system measures upward vertical velocity of the exercise weight by means of mechanically coupled sensor. Using known mass (input prior to the exercise), the system determines the power in the concentric phase of the weight exercise. In this way, the system provides all the basic parameters of a weight exercise, i.e. force, velocity and power.
A barbell or weight exercise machine equipped with such a system is effectively a simple dynamometer. The parameters obtained allow not only monitoring of fatigue during exercise set, but also sophisticated assessment of strength capabilities.
Technical description
The system (FIG. 1) consists of 2 functional components, a velocity sensor unit and a microcomputer. The velocity sensor is coupled with a rotating reel tethered to the weight by means of fine nylon chord. Backward movement of the reel is provided by means of string mechanism with resistance lower than 2 N. The tether can be extended to a maximum distance of 2.5 meter.
Function
Microcomputer with an alphanumeric display (FIG. 2) can be controlled by means of 4 keys. After switching the unit on, weight of the barbell or stack is to be set using arrow keys. After each repetition, its serial number, velocity in m/s and power (in W or percentage of the best repetition in a particular set of reps) are displayed. Data from up to 15 repetitions can be stored and later retrieved from the memory. The system can thus be used to monitor fatigue in a set of weight exercise. During performance of a set of repetitions, the power in the best repetition will be set as 100 %. The power of subsequent reps will be displayed also as percentages of this nominated maximum. The repetition with power below or above the predetermined upper and lower percentage levels (for example 90 % and 70 %) will be indicated by means of different acoustic signals. Should the second or a subsequent repetition received a higher power output than the nominated maximum, this new figure will be set as the 100 % figure against which subsequent reps will be compared. The system thus provides feedback information allowing to keep power in concentric phase in desired range. Pressing RESET key clears the memory, recalls the weight input mode and makes system ready for the next exercise set.
Application in assessment of strength capabilities
A typical test routine consists of maximal effort repetitions with stepwise increasing weights up to the 1RM. For instance, in bench press a starting weight of 20 kg is increased initially in steps of 10 kg. As the weight approaches 1RM, smaller increments, e.g. 2.5 or 5 kg, may be more appropriate. From each repetition, the mass, mean force, mean velocity and mean power are recorded. From these data, velocity vs weight and power vs weight curves as well as force vs velocity and power vs velocity curves, can be drawn (FIG. 3 and FIG . 4).
Not only the estimation of the maximal power but also the assessment of the force and power at velocities close to those in sports specific movement can be made (FIG. 5 and FIG. 6).
This approach provides a more sensitive method for detecting specific adaptations due to different forms of weight training (e.g. slow or fast) than the estimation of the sole 1RM.
Application in feedback monitoring of strength training
Particular repetitions in an exercise set with a given weight can be performed with different velocities and also with different power output in concentric phase. Although the same weight is used, different physiological mechanisms are involved and, hence, different adaptation processes can be expected.
Resistance training focused on the improvement of explosive power requires an intensity of exercise close to one´s maximum to guarantee recruitment of all, namely FTG, muscle fibers. Repetitions performed at below certain critical level of maximal power (e.g. 90 %), either because of lower motivation or fatigue, do not optimally stimulate improvement of explosive power. The ability to perform repetitions at close to one´s maximum is individual and depends on a variety of factors, predominantly on the ratio of fast and slow twitch fibers (FIG. 7). FiTROdyne provides the feedback information on power not only in absolute, but also as the percentage of the best repetition. In addition, an acoustic signal indicating that the power is less than a preset critical level is an additional facility. This indicates that fatigue has exceeded an acceptable level and a rest interval is necessary. The implementation of such philosophy, facilitated by FiTROdyne, substantially increases the efficiency of resistance training. FiTROdyne may be used with barbell or most weight exercise machines.
Fitro dyne may be applied for the assessment of strength capabilities and feedback monitoring of strength training in fitness gyms and studios, exercise laboratories, sports clubs , rehabilitation clinics etc.
FITRODYNE, COMPUTER BASED SYSTEM FOR STRENGTH DIAGNOSTIC AND FEEDBACK MONITORING OF WEIGHT TRAINING
FiTROdyne is a system working on the simple principle of mechanics saying that actual force is a product of acceleration and mass.
(Since the velocity and acceleration change during the lifting exercise, so does the actual force and also the other variables, e.g. power. Therefor, lifting the same weight in a more dynamic way with pronounced acceleration produces a higher peak force than a slowly performed lift. Also counter movement exercise produces much higher peaks than lift from rest position. Differences in parameters like force and power (which may be well quantified by this system) due to different physiological mechanisms involved in control of muscle contraction. One may, therefore, expect also different adaptation patterns.)
Acceleration of vertical movements (above or below g) is being obtained by derivation of vertical velocity, measured by highly precise analogue device mechanically coupled with a barbell or weights of an exercise machine (also complex lifting movement like clean and jerk or snatch can be monitored). In addition, power is being calculated as a product of force and velocity, the actual position by integration of velocity.
However, to be able to carry out these calculation, you have to enter mass of barbell or weights on the exercise machine first.
Construction
Technically the system consists of 2 functional components, a sensor and an electronic unit, stored in a small box of about 28x13x7,5 cm.
The sensor unit contains a precise analog velocity sensor and an infrared impulse sensor with resolution of 3 mm. Both are mechanically coupled with the reel. While pulling the tether out of the reel, this rotates and velocity is being measured. Back movement of the reel is guaranteed by string producing force of about 2 N. The tether can be pulled out to the distance of about 2.5 meter.
The other end of the tether is to be connected by means of a small hook either to the barbell axis or to the weights of the weight exercise machine. The attachment is easy and does not take more than several seconds.
The electronic box, contains the signal modification part, a 12 bit AD convertor and an acoustic device for differential signalization of reaching preset lower and upper positions during exercise (range of motion) as well as decrease of power under preset level. Use of signalization is optional, you can switch it on or off in a software setup.
The electronic box communicates with the computer by means of COM1. You can use any IBM-compatible computer (even 286), clock speed does not play any role. The only requirement is a VGA card and a VGA monitor (color or monochrome).
Software
Comprehensive software allows you to collect, calculate and on-line display the basic biomechanical parameters involved with the weight exercise. Of course you can store the data for further analyses of single repetitions or the whole set.
During the diagnostic measurement a movement of symbolic barbell axis and graph of any of derived parameter, i.e. velocity, force, power or acceleration. After each repetition you receive a summary of mean and peak data in digital form, separately for eccentric and concentric phase.
Typical test routine consists of a set of full effort repetitions from lower weights (e.g. 20 kg in bench press) with steps of 10 kg up to the maximum. There is a special menu driven software routine for this procedure. From such a test series you can obtain the individual force-velocity and power-velocity curves allowing you to assess the force and power at the velocities close to the velocities at sports specific movements. Such an approach provides a more sensible method for detection of specific adaptation changes due to various forms of weight training (e.g. slow or fast) than simple 1RM.
Should you wish to analyze the single repetition you may assign any of the parameters (force, power, velocity, acceleration, position and time) to either the X, Y1 or Y2 axis. Scaling, i.e. definition of minimum, maximum and step of parameter on all 3 axis is available. In addition, while moving the left and right cursors, the digital values of parameters on the X, Y1 and Y2 axis are being displayed. Also integral and mean values between both cursors are being actualized.
Such an analysis may for example demonstrate nicely the differences in time course of force, power and velocity between repetitions performed in slow or fast way, with or without counter movement, etc.
There is also a software routine available allowing you to use the system as a feedback for weight training. After each repetition you can see the decline of power output if performed in an all-out way. Drop under preset critical level will be indicated visually as well as by an acoustic signal. The patterns can be very different according to individual morphological dispositions (FT/ST muscle fiber ratio). In this way you can obtain some information about the quality of strength training stimuli. Also this information can be stored for the subsequent analyses.
The calibration of the system is software driven and basically very simple. This is due to simultaneous registration of velocity and distance. According to instructions on the screen you only have to pull the tether the defined distance between 50 and 100 cm (system calibrates the distance) and then to pull at least 50 cm with medium velocity (system calibrates the velocity). The calibration is in fact stable, a recalibration is necessary only if you use an exercise machine, in which - due to other than 1:1 levering - the weights are moved with different velocity than axis at which force is being applied. In this case you move the axis while performing calibration.
