petrofsky4-vol5no1 3/5/05 6:11 pm page 177 …...exercise is rhythmic,anaerobic metabo-lism...

The Journal of Applied Research • Vol. 5, No. 1, 2005 177

Assessment of the StaticComponent of Aerobic Exercise:A Comparison of Exercise UsingCycle and Treadmill Ergometry,Hip Extension Exercises With orWithout Gliding, and Gliding Video Workouts Jerrold S. Petrofsky, PhD, JDJennifer Hill, BSAshley HansonAmy Morris, BSJulie Bonacci, BS Rachel Jorritsma, BS

Department of Physical Therapy, Azusa Pacific University, Azusa, CaliforniaDepartment of Physical Therapy, Loma Linda University, Loma Linda, California

rpm, 60 rpm, and 90 rpm. On the tread-mill, work was performed against loadsof 1500 and 2500 kg meters per minute,and the grades were 5%, 10%, and15%. The results showed that work onthe cycle ergometer at the lowest rpmand work at the highest incline on thetreadmill were comparable. Work at thelowest and slowest loads required thehighest energy consumption and causedthe greatest increase in blood pressure,while heart rate only increased modest-ly when compared to these same meas-urements during a high-speed workout.This confirms the high static componentof slow speed work. Using this informa-tion as the baseline, the static compo-nent of aerobic exercise during usingthree different Gliding exercise videos

KEY WO R D S : e x e r c i s e, e x e r t i o n ,a e r o b i c, f i t n e s s.

ABSTRACTFour subjects, whose ages averaged 24.3years, were examined to assess the iso-metric component of dynamic exerciseduring the following 4 conditions: tread-mill running, cycle ergometry, aerobicexercise following a video, and duringhip extension exercise (lunges). The iso-metric component of exercise was char-acterized by examining heart rate (HR)and blood pressure (BP), muscle fatigue,oxygen consumption, and lactic acid pro-duction. Work on the cycle ergometerwas against loads of 300 kg and 600 kgmeters per minute at cycle speeds of 30

Petrofsky4-vol5no1 3/5/05 6:11 PM 77

Vol. 5, No. 1, 2005 • The Journal of Applied Research178

and during lunges with or withoutGliding disks were calculated. Lungeswith Gliding disks were associated withapproximately a 20% increase in oxygenconsumption and heart rate, and approx-imately a 30% reduction in hamstringand quadriceps muscle strength during 5minutes of exercise compared to regularlunges without Gliding. The static com-ponent and total workloads weregreater. In the exercise using the 15-minute, 13-minute, and 8-minute exer-cise videos with gliding, there was a highisometric component, which caused asubstantial reduction in muscle strength.Exercise using Gliding disks with thevideos has a high static component andprovides a good aerobic training.

INTRODUCTIONIt is hard to envision exercise that isstrictly either dynamic or isometric incharacter. Dynamic exercise oftenresults in a large increase in heart rateand ventilation, while mean blood pres-sure does not change during the work-out.1,2 The increase in respiration, heartrate, and blood pressure associated withdynamic exercise is due in large part toa mechanism called reflex in nature.3

Depending on the frequency of exercise,there is some variability in ventilationand circulation during dynamicexercise.4 While there is some differenceassociated with muscle fiber composi-tion in these responses,5 they are usuallysimilar when compared to work normal-

ized as a percent of the maximum oxy-gen consumption max VO2, in both menand women and irrespective of race.2

At the other end of the spectrum isexercise where the muscle does notchange length. This type of exercise iscalled isometric exercise. During isomet-ric exercise, the ventilation increase ismodest (a few liters per minute) butgreater than that needed for oxygendelivery, thereby causing hyperventila-tion.1 Systolic and diastolic blood pres-sure show a progressive and steadyincrease throughout the duration of theexercise such that blood pressure canincrease by 50% or more during a 2minute fatiguing isometric contraction.6

A further delineating factor in isometricexercise is the fact that during isometricexercise, muscle strength decreasessteadily throughout the exercise whereasduring dynamic exercise strength is onlymarginally reduced unless the exercise isdone to fatigue.6

When dynamic exercise is conduct-ed slowly and against a heavy load (iso-kinetic exercise), even though theexercise is rhythmic, anaerobic metabo-lism dominates and the cardiovascularresponses are closer to isometric thendynamic exercise.7 Thus in exercise suchas rock climbing, cardiovascular respons-es may not correlate well compared topure aerobic exercise such as cycleergometry at 60 rpm.8 In dynamic exer-cise, there is less of an increase in heartrate and muscle heat production is high-er during repeated bouts of exercise

Table 1. General Characteristics of Subjects

Age Height Weight Resting Resting BP* Resting (years) (cm) (kg) Heart Rate (Systolic) BP

(Diastolic)Mean 24.3 169.4 63.3 81.01 110.5 64.3SD 0.5 5.8 10.3 15.1 6.4 4.4

*BP indicates blood pressure.

Petrofsky4-vol5no1 3/5/05 6:11 PM Page 178


against heavy loads, than during highspeed dynamic exercise.9,10

However, a previous study mayexplain these results. Petrofsky et al11

examined the static component of rhyth-mic exercise. In these experiments, cycleergometry was accomplished at thesame absolute workload either at slowspeeds (30 rpm), moderate speeds (50rpm), or high speeds (90 rpm). For exer-cise at 90 rpm, the body exhibitedresponses associated with pure dynamicexercise whereas, at low speeds, musclesfatigued rapidly. Although the work-loads were the same for all speeds, therewas a lower heart rate response, lessoxygen uptake, and greater musclefatigue at low speed workouts comparedto high-speed workouts even thoughworkloads were matched. Thus, slowdynamic exercise may provide goodstrength training, although dynamicexercise is inherently known for cardio-vascular effects and not for strengthtraining.2

In summary, while isometric exerciseis a pure form of exercise and the car-diorespiratory responses are predictable,the cardiovascular responses to dynamicexercise are not fixed, but show a spec-trum of responses from that of very slowand heavy isokinetic exercise where thecardiovascular responses are similar toisometric exercise to high speed lowload dynamic exercise where the heartrate and cardiac output increase greatlywhile muscle strength, and blood pres-sure respond more modestly. For exer-cise involving moderate loads atmoderate speeds, the responses arebetween these extremes.11

Therefore, it seems reasonable thatmany types of exercise, which involvestabilization of the core muscles such aslunges (hip extension, flexion andadduction abduction exercises), have asignificant static component, since to sta-bilize the core of the body, the abdomi-nals and paraspinal muscles must be

engaged in an isometric contraction tokeep the trunk stable. The purpose ofthis study was to quantify the static com-ponent of rhythmic exercise during exer-cise videos and lunges compared to cycleergometry and treadmill exercise. Twotypes of lunges were examined. Onewhich involved hip extension on alter-nate sides of the body and the other,which still involved hip extension, butincluded the use of “Gliding” disks toallow the leg to move with low friction,thereby providing continuous muscleactivity throughout the lunge exercise.19

Three different exercise videos involvingGliding were also evaluated.

SUBJECTSThe subjects were 4 females. Their char-acteristics are summarized in Table 1.All subjects were fit thoroughly trainedin treadmill, cycle ergometer, and aero-bic lunge exercises. All subjects werefree of cardiovascular or orthopedicimpairments and all subjects had theexperimental procedures explained tothem and signed a statement ofinformed consent approved by theHuman Review Committee at AzusaPacific University.

METHODSStrengthIsometric strength of the quadriceps andhamstrings muscles was measured withthe subjects in the seated position andthe leg held at a 90˚ angle. To accomplishthis, a woven cotton belt was placedaround the ankle and connected to anisometric strain gauge transducer bar.The strain gauge was linear in the rangeof 0 kg to 200 kg of force. The output ofthe transducer was amplified with astrain gauge conditioner amplifier with again of 1000. The output was stored andanalyzed as the average strength overthe middle of a 3 second maximum contraction.



Oxygen Consumption, Ventilation,Carbon Dioxide Production,Respiratory QuotientA VO-2000 portable metabolic cart(Aerosport Inc., Minneapolis, Minn) wasused in these studies. The analyzer iscomposed of a battery operated meta-bolic cart containing a CO2 infrared ana-lyzer, a fuel cell based oxygen analyzer,and a pneumotach (Figure 1). The ana-lyzer was calibrated with the local baro-metric pressure and temperature at thebeginning of each day. The analyzersampled expiratory gases through amouthpiece. The subjects wore a noseclip to assure all expiratory gassespassed through the pneumotach. The gaswas sampled breath by breath and all

gas values were averaged over a 20-sec-ond period. Ventilation, oxygen con-sumption, and carbon dioxideproduction were then converted to stan-dard pressures and temperatures(STPD) and stored in the memory ofthe analyzer.

Blood Lactate An Accusport fingertip lactic acid ana-lyzer measured blood lactate. The bloodsample was taken from arterializedblood in the subject’s fingertip 5 minutesafter exercise; total blood volume was 25µL. Blood was arterialized by placingthe hand in warm water for 5 minutes,immediately following exercise, beforethe sample was taken (Figure 2).

Heart RateHeart rate was recorded from palpita-tion of the radial pulse.

Blood PressureBlood pressure was measured by auscul-tation of the left arm with a blood pres-sure cuff. The cuff was pumped to 200mmHg and deflated at 3 mmHg per sec-ond as per the standards of theAmerican Heart Association. Systolicblood pressure was assessed as the firsttapping sound heard through a sphyg-momanometer in the anacubical fossa.Diastolic pressure was the change inpitch from the high pitch tapping to amurmur. The same person measuredblood pressure on all occasions (Figure 3).

Statistical AnalysisStatistical analysis involved the calcula-tion of means, standard deviations, andpaired and unpaired t tests. The level ofsignificance was P < 0.05.

PROCEDURESFour series of experiments were accom-plished. In the first series of experi-ments, the relationship between oxygen

Figure 1. A pneumotach is used to measureoxygen consumption and ventilation on asubject exercising. A nose clip is used toensure airflow through the mouth only.



consumption, heart rate, blood pressure,and muscle fatigue in the quadricepsand hamstring muscles was determinedduring treadmill running. Treadmill run-ning was performed at 2 different work-loads with the treadmill set at 3 differentgrades (5%, 10%, and 15%) (Table 2).The speed was adjusted for each individ-ual, so that workloads were matched ateach grade at either 1500 kg meters perminute or 2500 kg meters minute.Because of differences in body weight,the speed was different for each subject.Table 2 shows the average speeds ateach grade with the standard deviationsfor the group. In this manner, on thetreadmill, the same workloads and thecardiovascular responses could be meas-

ured with fast running at a low incline,versus high incline and slow running.Subjects exercised for periods of 5 min-utes and between the fourth and fifthminute of exercise, oxygen consumption,respiratory quotient, and ventilationwere measured. After the exercise wasover, lactates, blood pressure, and heartrate were assessed, as were changes inthe muscle strength in the quadricepsand hamstring muscles (Figure 4). Thestrength was measured within a few sec-onds after the end of each exercise.

In the second series, the experi-ments were repeated on a cycle ergome-ter. Speeds of 30 rpm, 60 rpm, and 90rpm were used with various workloadsto allow work at 300 kg meters/min and

Figure 3. Blood pressure measured on a studysubject.

Figure 2. A subject’s hand is placed in warmwater on a hotplate to arterialize the bloodin the fingertip prior to sampling blood forlactic acid determinations.



600 kg meters/min for each speed (Table3). Protocols were similar to thoseabove. Subjects exercised for periods of5 minutes and between the fourth andfifth minute of exercise, oxygen con-sumption, respiratory quotient, and ven-tilation were measured. After theexercise was over, lactates, blood pres-sure, and heart rate were assessed, aswere changes in the muscle strength inthe quadriceps and hamstring muscles.

In the third series of experiments,subjects engaged in exercise involvingalternating leg hip extension (lunges)with or without discs (Gliding) underthe foot to reduce friction upon move-ment (Figure 5).

Finally, in the fourth series of exper-iments, subjects followed a video exer-cise program provided by Savvier LP(Santa Fe Springs, Calif). Subjects usedGliding disks to minimize kinetic fric-tion between the body and the floor.Gliding, by minimizing friction, allowssmooth muscle contraction duringmovement in any direction with continu-ous muscle activity (Figure 5).19 Thevideotape was divided into 3 segments.The first (15 minutes) and second (13minutes) Gliding segments involved

rhythmic lunge sequences in the stand-ing position. The third Gliding segmentinvolved exercise on the floor in theprone and side lying positions for a totalof 8 minutes. For each segment, theparameters above were measured in thefourth, fifth, and last minute of exerciseexcept for strength and lactate measure-ments, which were done at the end ofthe exercise.

RESULTSTreadmill ExerciseThe results of the studies on treadmillergometry are shown in Figure 6. Heartrate was highest and blood pressure low-est during a workout at a 5% grade. Theaverage increase in heart rate duringexercise at a load of 1500 kg meters perminute was 22 ± 9.38 beats per minutefor work at a 5% grade (Figure 6B). At2500 kg meters per minute of resistance,the heart rate increased by 43.5 ± 23.69beats per minute. In contrast, exercisewith the treadmill (Figure 7) at a 15%grade showed a more modest increase inheart rate, 15 ± 4.76 beats per minute atthe lowest load, and 27.5 ± 7.63 beatsper minute at the moderate load. In con-trast, systolic blood pressure was highest

Table 2. Average Speeds Used for the Treadmill

Speed 5% grade Speed 10% grade Speed 15% grade (miles/hour) (miles/hour) (miles/hour)

Low mean 1.8 0.9 0.6Low standard deviation 0.3 0.1 0.1Medium load 5.9 3.0 2.0Medium standard deviation 1.0 0.5 0.3

Table 3. Workloads on Cycle Ergometer

Low resistance Moderate resistance (300 kg m/min) (kg m/min)

30 rpm 1.67 3.3360 rpm 0.83 1.6790 rpm 0.56 1.11



for the moderate workload at a 15%grade. For example, the change in sys-tolic blood pressure at the moderateworkload for the 15% grade was 19.5 ±8.02 mmHg compared to 10.0 ± 2.94mmHg for the same workload at the 5%grade. Thus, for the cardiovascularresponses, matched workloads at a 15%grade resulted in a greater increase inblood pressure, but had less effect onheart rate compared to matched work-loads at the lowest grade examined.These differences were significant (P <0.01). Workloads at the 10% grade fellbetween the two extremes. Diastolicblood pressure was not significantly dif-ferent at any workload examined. (P >0.05, ANOVA)

The greatest increase in lactates

occurred at the 15% grade and at amoderate workload (15% grade, 2500 kgmeters per minute workload). Here, theaverage lactates increased by 2.3 ± 1.4mmoles/L compared to the similarworkload at a 10% grade, where lactatesonly increased by 0.88 ± 0.4 mmoles/L.At the same workload at the 5% grade,the lactates increased much more mod-estly by 0.05 ± 0.23 mmoles/L. Whenmuscle strength was measured beforeand after exercise at the 6 workloadsexamined here, there was a reduction instrength for both the quadriceps andhamstrings muscles after all workloads.Prior to exercise, the average strength of

Figure 5. A subject using Gliding to accom-plish backward lunges. When the heel isplanted on the floor (front) one leg is fixedand cannot move, with the heel lifted,Gliding provides very low friction, so that theleg can traverse into extension and flexionwith continuous smooth muscle activity.

Figure 4. Hamstring muscle strength meas-ured immediately after an exercise bout.



the quadriceps muscles during extensionof the leg, measured at the ankle, was61.17 ± 17.6 kg. For the hamstring mus-cles, the average strength was 42.6 ± 5.93kg. At the end of the exercise, the reduc-tion of the quadriceps muscle strengthwas greatest for workloads at the 15%grade and lowest for exercise at the 5%grade. For example, at the lowest grade(5%), the reduction in quadricepsstrength was 2.5 ± 1.08 kg for the lowworkload, whereas the reduction was 4.0± 3.2 kg for the moderate workload. Incontrast, for exercise at the highestgrade (15%), the reduction was 7.5 ± 5.0kg for the low workload, and 12.8 ± 9.3kg for the moderate workload. The samerelationship was seen for the hamstringmuscles (Figure 6C). There was a sharpreduction in the strength of the ham-

string muscle associated with all work-loads. Expressed as a percent, at a 5%grade, there was a 2.48% loss in strengthfor the low workload compared to a5.88% loss for the moderate workload.For the 10% grade, there was a loss instrength of 6.1 after the low workloadand 10.1% after the moderate workload.At a 15% grade, the reductions instrength were 7.4% after the low work-load and 17.2% after the moderateworkload.

The respiratory responses showed asimilar pattern. The oxygen consumptionwas greatest for work at a grade of 5%and lowest for a grade of 15% (Figure6D). When subjects ran at a grade of 5%with a moderate workload, the oxygenconsumption averaged 1.29 L/minute(6.45 calories), whereas the oxygen con-

Figure 6. A) Heart rate, B) systolic blood pressure, C) hamstring strength, and D) oxygen con-sumption during exercise on a cycle ergometer at speeds of 30 rpm, 60 rpm, and 90 rpmagainst workloads at each speed of 300 and 600 Kg meters/min.



sumption at a higher grade (15%) aver-aged only 0.83 L/minute (4.15 calories)in the last minute of exercise (Figure6B). During this same period, at themoderate workload, ventilation showedsimilar responses with ventilationagainst a 5% grade increasing to 35.6 ±15.4 L/min, whereas at a 15% grade ven-tilation was 19.36 ± 1.56 L/min.

Cycle Ergometer ExerciseThe results of the experiments on thecycle ergometer are shown in Figures7A, B, C, and D. The largest increase inheart rate was after work at 90 rpmcompared to matched work at either 30rpm or 60 rpm (Figure 7A). The differ-ences between the low workloads at 30rpm, 60 rpm, and 90 rpm were statistical-ly significant, as was data for the moder-ate workloads at 30 rpm, 60 rpm, and 90rpm (P < 0.05). The increases in heartrate for work at 90 rpm was nearly dou-ble that of 30 rpm. The same was trueconcerning blood pressures (Figure 7B).The average systolic blood pressure forthe group was much higher for work at30 rpm than 90 rpm. This difference wasstatistically significant (P < 0.05). Forexample, at a moderate load, at 30 rpmthe average increase in systolic bloodpressure was 55.3 ± 11.8 mmHg, whereasat 90 rpm, the increase in systolic pres-sure was only 36.5 ± 6.2 mmHg. Thus ata moderate workload, the average bloodpressure for subjects increased from anaverage of 114 ± 2.4 mmHg at rest to anaverage of 150 ± 8.16 after work at 90rpm, but only increased to an average of168.8 ± 10.3 mmHg at 30 rpm.Therefore, as was the case for treadmillergometry, the cardiovascular responseswere a function of the speed of work.

At a moderate workload, the great-est increase in lactates occurred at 30rpm; the average lactates increased by3.9 ± 5.3 mmoles/L compared to 60 rpmwhere lactates only increased by 1.4 ±2.1 mmoles/L. At 90 rpm, the lactates

increased much more modestly by 0.17 ±0.91 mmoles/L.

Changes in strength were alsotelling. For the group, the averagereduction in strength was greatest at 30rpm compared to 60 rpm and 90 rpm;these differences were statistically signif-icant (ANOVA, P < 0.01) (Figure 7C).The greatest reduction in strengthoccurred at 30 rpm at the moderateworkload. For the quadriceps muscle, forexample, muscle strength was reducedfrom the initial average of 75.5 ± 20.4 kgbefore exercise to 59.8 ±17.7 kg aftermoderate exercise at 30 rpm, a loss of15.8 ± 3.5 kg. In contrast, after the samemoderate work at 90 rpm, strength ofthe quadriceps muscle was reduced by7.75 ±13.0 kg, a much more modestreduction in strength. The same relation-ship was seen for the hamstring muscles(Figure 7C). Here the greatest reductionin strength for either the low or moder-ate workload was at the lowest rpm.These differences for the hamstringmuscle between the three differentcycling speeds are statistically significant(P < 0.01).

Finally, the greatest oxygen con-sumption and ventilation occurred afterexercise at 90 rpm (Figure 7D). Oxygenconsumption was highest after exerciseat 90 rpm and lowest at 30 rpm; whencomparing the oxygen uptake during thelow workload at 30 rpm versus 60 rpmversus 90 rpm, the differences were sta-tistically significant (P < 0.01), as wasthe comparison of oxygen consumptionduring moderate workloads at 30 rpm,60 rpm, and 90 rpm (P < 0.01). For thelowest workload at 30 rpm, the increasein ventilation was 15.83 ± 0.92 L/min,whereas at 90 rpm, the increase in venti-lation averaged 35.83 ± 9.1 L/min. Thusfor ventilation and oxygen consumption,the greatest demand on the respiratorysystem was at 90 rpm with the demandat 30 rpm being only about 50% of thatat 90 rpm.



Exercise Videos And Lunges Data from the third and fourth series ofexperiments have been analyzed togeth-er, since both involved Glides (Figures 8and 9).

The increase in heart rate associatedwith 5 minutes of hip extension (lunges)with Gliding or without Gliding, and fol-lowing the Gliding videos lasting 15minutes, 13 minutes, and 8 minutes areshown in Figures 8 and 9. There was nostatistical difference in oxygen consump-tion, heart rate or ventilation during aer-obic exercise during the 3 Glidingexercise videos, when comparing thedata at 5 minutes to that in the lastminute of exercise (P > 0.05). Therefore,

only data in the last minute is presentedin the paper.

The heart rate was substantiallyincreased for all five types of exercise.Comparing 5 minute hip extension datawith Gliding (HEG) to without Gliding(HE), the increase in heart rate aver-aged 54.0 ± 10.9 beats/minute at the endof 5-minutes HEG compared to 30.0 ±14.7 beats/min at the end of HE. The dif-ference between the two was significant(P < 0.01) (Figure 8A). In contrast, theaverage heart rate at the end of Glidingexercise using the 15-, 13-, and 8-minutevideos was greater than that of lunges,but similar to that of Gliding lunges. Thedifference between the heart rate, for

Figure 7. A) Heart rate, B) systolic blood pressure, C) hamstring strength, and D) oxygen con-sumption during exercise on a treadmill against a grade of 5%, 10%, and 15% with low and mod-erate exercise loads.



lunges with or without Gliding, orGliding using the 15- and 13-minuteexercise videos, were not statistically sig-nificant (P < 0.05). However, the heartrates at the end of the Gliding exerciseusing 8-minute video were greater thanafter lunges without gliding, but lessthan after lunges with Gliding (P < 0.05)The diastolic blood pressure was unaf-fected by any of the different exercises.However, the systolic blood pressure

was statistically higher for HEG than forHE (P < 0.05) (Figure 8B). Systolicblood pressure at the end of Glidingexercise, using the 13- and 8-minutevideos, was not different than at the endof lunges without Gliding (P > 0.05), butless than that of the 15-minute videoexercise using Gliding (P < 0.05).

The lactates recorded after thebackward lunges without the glidesaveraged 0.4 ± 1.1 mm/L, whereas for

Figure 8. The change in heart rate (A) and systolic blood pressure (B) during 5 minute bouts ofhip extension Gliding, 5-minutes of hip extension lunges, and exercise using the 15-minute, 13-minute and 8-minute video Gliding exercise programs.



back lunges with the glides, the averagelactates were 0.7 ± 0.34 mm/L. In con-trast, for the 3 Gliding exercise videos,the lactates at the end of exercise were1.1 ± 1.29, 0.63 ±1.09, and -0.05 ± 0.13mm/L for the 15-, 13- and 8-minute exer-cise segments, respectively.

As shown in Figure 9, the reductionin strength of the quadriceps and ham-strings muscles was greatest duringGliding lunges and after using the 15-

minute Gliding exercise video and low-est after back lunges and the using the13- and 8-minute Gliding exercisevideos. For example, for the quadricepsmuscle, the reduction in strength afterlunges with Gliding was 9.3 ± 6.9 kgwhereas after the lunge exercise it was3.2 ± 3.6 kg. Hamstring data showed asimilar reduction (Figure 9A). The dif-ference between the strength in thequadriceps and the hamstring muscles

Figure 9. The change in hamstring strength (A) and oxygen consumption (B) during 5 minutebouts of hip extension Gliding, 5-minutes of hip extension lunges and exercise using the 15-minute, 13-minute and 8-minute video Gliding exercise programs.



after the lunges with Gliding versuslunges was statistically significant (P <0.05).

Oxygen consumption was higherduring lunges with Gliding than lungeswithout gliding. The average oxygenconsumption for the group after thelunges with Gliding averaged 0.76 ± 0.18L/min (3.8 ± 0.9 calories) and afterlunges without gliding averaged 0.59 ±0.11 L/min (2.95 ± 0.55 calories).

Of the 3 Gliding exercise videos,oxygen consumption was highest for the15-minute video, almost as high for the13-minute video, and lowest for the 8-minute video (Figure 9B). The respirato-ry quotient during the 3 videos, averaged0.79 ± 0.6 demonstrating that the exer-cise was supported by the metabolism oflipids.

DISCUSSIONThe benefits of sustained bouts of exer-cise for health and physical conditioningare well documented.12,13,14 While exer-cise is difficult for people with disabili-ties,15 even in patients with heart failure,exercise training improves mortality andreduces morbidity.16

However, what is called aerobicexercise in many of these studies is actu-ally a complex combination of stress onanaerobic and aerobic metabolic path-ways. Slow exercise conducted rhythmi-cally still has a considerable isometriccomponent.11 Exercise conducted at lowcontraction frequencies and high loadsversus high frequencies and low loadsare characterized by very different phys-iological responses even if the work ismatched.10,11 For example, for slow exer-cise conducted at a heavy load, bloodpressure and ventilation are higher andmuscle fatigues more rapidly than forhigh speed work at light loads.6,11 Thegreater demand placed on the anaerobiccapacity of the muscle by slow exercisemay be partially due to the fact that dur-ing dynamic exercise, especially with

heavy loads, muscle is perfused poorlydue to high intramuscular pressure.17

Slow aerobic exercise, by decreasingmuscle strength, adds a strength trainingcomponent to dynamic exercise.18,11 Incontrast, aerobic exercise at a light loaddoes little to build muscle strength, butis a good for building aerobic capacity.2Thus a workout program involving slowheavy exercise and fast light exercisetogether should provide both cardiovas-cular conditioning and strengthening ofthe muscle.

In the present investigation, therelationships reported previously incycle ergometry were confirmed con-cerning a high loss in muscular strengthwith slow rhythmic exercise.11 Cycleergometry conducted at a slow rate butheavy load resulted in considerable pro-duction of lactic acid and a dispropor-tional increase in ventilation, heart rateand blood pressure during exercise. Incontrast, cycle ergometry at a high ratebut low load produces only smallchanges in mean blood pressure and lit-tle lactic acid. This same relationshipwas seen in treadmill ergometry. On thetreadmill, running at a 15% grade result-ed in considerable losses in musclestrength and increases in blood pressure,ventilation, and heart rates, as well aslactic acid production, all indicative of ahigh component of anaerobic or staticexercise. Exercise at the same work-loads, with the treadmill at a lowergrade, even at matched workloads, pro-duced much less of an increase in lacticacid, oxygen consumption, and loss ofmuscle strength. This confirms the lowstatic component of the exercise.

It is not surprising, then, that amixed workout, which is, comprised of a15-minute exercise period of high- andlow-speed aerobic exercise involvingGliding falls in between the two. Thereduction of muscle strength and thechanges in heart rate and ventilationshow that this form of exercise falls in



the middle of the two, being a mixture ofanaerobic (static) exercise, which buildsmuscle strength, and pure aerobic exer-cise, which tones the cardiovascular sys-tem. Using cardiovascular measures, amixed exercise is quantified in terms ofits anaerobic and aerobic component.This static component of rhythmic exer-cise is essential to compute in any exer-cise program to minimize the timeneeded for training. With the reductionsin muscle strength in such a program, aseparate weight lifting program wouldnot be a necessary, since the exerciseitself becomes a total body workout.

For Gliding, the heart rate increasewas slightly greater than that of themoderate workload on the treadmill(3500 kpm/minute) at a 5% grade. Sinceexercise at a 5% grade is associated withpure aerobic exercise with little staticcomponent, this would seem to implythat Gliding is associated with a largestatic component. However, the increasein blood pressure was 35 mmHg andequivalent to exercise at a 15% grade onthe treadmill or cycle ergometer (Figure8B). Further, on the treadmill, the loss inhamstring strength was greater than thatseen at a 5% grade, but almost equiva-lent to the moderate load at the 15%grade. This is also true of oxygen con-sumption, which was low for the level ofheart rate shown and muscle loss seen inthe exercise. Thus, Gliding is a mix ofaerobic exercise with a high isometric orstatic component. This high static com-ponent will provide good strength train-ing along with endurance training duringGliding lunges. The opposite was true ofregular lunges where the loss in strengthwas equivalent to almost pure aerobicexercise on either the treadmill (Figure6) or cycle ergometer (Figure 7), whilethe work was much less.

The results of exercise following the15-minute video, which involved exer-cise in the standing posture withGliding, showed a greater increase in

oxygen consumption and a greater lossin strength than with the 13-, and 8-minute Gliding videos. Oxygen use (0.8L/minute, 4 calories) during treadmill orcycle ergometry, increased to 0.8 L/perminute (4 calories) for pure aerobicexercise with a low static component(eg, exercise on the treadmill up to 5%grade or on the cycle ergometer at 90rpm) and would cause significantly lessstrength loss than Gliding. The greaterloss in strength along with greaterincrease in systolic blood pressure withGliding exercise using the video wouldindicate that this video exercise has ahigh muscle strength-training compo-nent. This was also seen with the 13-minute and 8-minute Gliding videoexercise but to a smaller extent. The 8-minute Gliding video exercise appearedto be higher in the pure aerobic exercisecomponent than exercise with the 15-minute video. However, exercise follow-ing all three Gliding videos did have amuch higher isometric component thantreadmill ergometry against a 5% gradeor bicycle ergometry at 90 rpm.

Comparing treadmill ergometry tothe exercise following the 15-minuteGliding video, the response of oxygenconsumption and reductions in strengthusing the video workout seemed to beequivalent to exercise on a treadmillergometer at a 15% grade with the loadof 2500 kpm/minute (Figures 6 and 9).The easiest workout, following the 8-minute video, corresponded to exerciseon a treadmill at a 15% grade and aworkload of 1500 kg/minute. In otherwords, the workout using the 15-minuteGliding exercise video was equivalent ofrunning up a 15% grade at two miles anhour, whereas exercise following the 8-minute exercise video was equivalent torunning up hill at .5 miles per hour(Table 2). On the other hand, theGliding exercise was highly aerobic innature, as demonstrated by oxygen con-sumption and lactic acid production.



Thus Gliding was in the middle of thespectrum between pure aerobic andpure weight lifting exercise, being a mix-ture of both. Therefore, exercise usingthese videos provided a heavy dynamicworkout as well as implied strengthtraining because of their high static com-ponent.

In 1998, The American College ofSports Medicine published guidelinesfor exercise levels to maintain cardiovas-cular fitness.20 They recommended exer-cising 3 to 5 days per week at anintensity of 55% to 65% maximum heartrate reserve or 4 METS or about 50%VO2 reserve for up to 60 minutes.21 Inthe present investigation, the Glidingvideo exercise could be analyzed severalways. In terms of METS, the averageresting oxygen consumption was 0.19liters per minute. The oxygen consump-tion using the 15-minute Gliding videowas 0.8 liters per minute or 4.2 METS.Thus under the METS classification, theworkload would be classified as moder-ate and would pass ACSM guidelines forcardiovascular training. The same wouldbe true of the 13-minute Gliding videoexercise.

Using heart rate, an increase of 60beats per minute would place the exer-cise in the moderate workload categoryas per ACSM guidelines for fitness. Theincrease in heart rate after the 15-minute video workout was only 55 beatsper minute and slightly less with theother 2 videos. Unlike most exercise,there was a high static component whenexercising using the 13- and 15-minuteGliding exercise videos, which causes areduction in heart rate to a value lessthan the equivalent workload with pureaerobic exercise. Thus by the heart ratestandard, exercise using the 15- and 13-minute Gliding videos meet the stan-dard for moderate exercise intensityrequired by ACSM guidelines. The 8-minute Gliding video exercise would be

classified as a light workout, using heartrate and oxygen consumption.

REFERENCES1. Wiley RL, Lind AR. Respiratory responses to

simultaneous static and rhythmic exercise inhumans. Clin Sci Mol Med. 1975;49(5):427-432.

2. McArdle WD, Katch FI, Katch VL. Energy,Nutrition, and Human Performance. In:Exercise Physiology. 5th ed. Philadelphia, Pa:Lippincott, Williams & Wilkins; 2001:chap 3.

3. Tallarida G, Baldoni F, Peruzzi G, RaimondiG, Massaro M, Sangiorgi M. Cadiovascularand respiratory reflexes from muscles duringdynamic and static exercise. J Appl Phsiol.1981;50(4):784-791.

4. Miyamoto Y, Nakazono Y, Yamakoshi K.Neurogenic factors affecting ventillatory andcirculatory response static and dynamic exer-cise in man. Jpn J Physiol. 1987;37(3):435-446.

5. Suzuki Y. Mean arterial pressure, O2-uptake,and muscle force time during dynamic andrhythmic-static exercise in men with high per-centage of fast- and slow-twitch fibers. Eur JAppl Phsiol Occup Phsyiol. 1980;43(2):143-155.

6. Petrofsky JS. Isometric Exercise and ItsClinical Implications. Springfield Ill: CharlesC Thomas; 1982.

7. Martin BJ, Chen HI, Kolka MA. Anaerobicmetabolism of the respiratory muscles duringexercise. Med Sci Sports Exerc. 1984;16(1):82-86.

8. Sheel AW, Seddon N, Knight A, MckenzieDC, Warburton DER. PhysiologicalResponses to Indoor Rock-Climbing andTheir Relationship to Maximal CycleErgometry. Med Sci Sports Exerc.2003;35(7):1225-1231.

9. Krustrup P, Gonzalez-Alonso J, Quistorff B,Bangsbo J. Muscle heat production andanaerobic energy turnover during repeatedintense dynamic exercise in humans. JPhysiol. 2001;536:947-956.

10. Furguson RA, Ball D, Krustrup P, et al.Muscle oxygen uptake and energy turnoverduring dynamic exercise at different contrac-tion frequencies in humans. J Physiol.2001;536:261-271.

11. Petrofsky JS, Rochelle RR, Rinehart JS,Burse RL, Lind AR. The assessment of thestatic component in rhythmic exercise. Eur JAppl Phsiol Occup Physiol, 1975;34(1):55-63.

12. Ko GT. Short-term effects after a 3-monthaerobic or anaerobic exercise programme inHong Kong Chinese. Diabetes Nutr Metab.2004;17(2):124-127.



13. Copeland JL, Chu SY, Tremblay MS. Aging,physical activity, and hormones in women—areview. J Aging Phys Act. 2004;12(1):101-116.

14. Raurmaa R, Halonen P, Vaisnen SB et al.Effects of aerobic exercise on inflammationand atherosclerosis in men: the DNASCOStudy: a six-year randomized controlled trial.Ann Intern Med. 2004;140(12):1007-1014.

15. Romberg A, Virtanen A, Aunola S, KarppiSL, Karanko H, Ruutiainen J. Exercise capac-ity, disability and leisure physical activity ofsubjects with multiple sclerosis. Mult Scler.2004;10(2):212-218.

16. Smart N, Marwick TH. Exercise training forpatients with heart failure: a systematicreview of factors that improve mortality andmorbidity. Am J Med. 2004;116(10):714-716.

17. Eiken O. Responses to dynamic leg exercisein man as influenced by change in muscleperfusion pressure. Acta Physiol Scand Suppl.1987;566:1-37.

18. Bloomer RJ, Goldfarb AH. Anaerobic exer-cise and oxidative stress: a review. Can J ApplPhysiol. 2004;29(3):245-263.

19. Petrofsky JS, Hill J, Jorritsma R, Bonacci J,Morris A, Hanson A. Muscle Use during LowImpact Aerobic Exercise (Gliding)Compared to Conventional Weight LiftingEquipment, Part 2. J Appl Res. In press.

20. Jakicic JM, Clark K, Coleman E, et al.Appropriate intervention strategies forweight loss and prevention of weight regainfor adults. Med Sci Sports Exerc.2001;33(12):2145-2145.

21. American College of Sports MedicinePosition Stand. The recommended quantityand quality of exercise for developing andmaintaining cardiorespiratory and muscularfitness, and flexibility in healthy adults. MedSci Sports Exerc. 1998;30:975-991.


petrofsky4-vol5no1 3/5/05 6:11 pm page 177 …...exercise is rhythmic,anaerobic metabo-lism...

Documents