Intensity zones on classical distances in amateur radio direction finding for 13-14 year-olds

PhD, Honorary Coach of the RSFSR K.G. Zelensky1
Dr. Hab., Professor G.N. Ponomarev2
1North Caucasus Federal University, Stavropol
2St. Petersburg State University, St. Petersburg


Keywords: amateur radio direction finding, heart rates, blood lactate content, anaerobic threshold, classical distance.


Background. A competitive distance profiling study in the amateur radio direction finding sport found [6] the distances in the top-ranking international competitions (European and World Championships) for the 13-14 years-old age group averaging 3800m with the total ascends of 80m, and with the athletes locating 3-4 radio transmitters for 35min on average. On the classical distances the radio transmitters operate in 5min cycles (1min on and 4min off), and these cyclic radio transmitters operation require from athletes to be highly physically and functionally fit since the run control range is very wide, with the high-intensity sections in the radio transmitters activation minute and slow run in the wait sections.

Generally an athlete shall give a top priority to the run control aspects so that to come reasonably close to the radio transmitters by the switch-on moment to be able to locate it for 1min [1]. The close location zone varies within the range of 100-300m depending on the terrain for this age group. The run intensity on the distance normally depends on the individual run control scenario and the radio transmitter locations. In case when, e.g., the close RL zone is 500m far and the radio transmitter is expected to switch on in 4min, the athlete shall run at 2.10 m/s, conditional on the radio transmitter being located only in the transmission time. When the close RL zone is 1000m far, the athlete shall run at some 4.16 m/s to reach the zone for 4min off-time. In the critical moments when the radio transmitter is on and may be fast found, the run speed may come to as much as 5.00-5.80 m/s [2]. No wonder that such cross-country races are highly demanding to the athletes’ physical and functional fitness rates including the energy supply system performance standards; and, hence, the precompetitive training and competitive performance control systems shall be prudently designed and supported by inflows of relevant and dependant performance data for success in the competitions.

Objective of the study was to profile and analyze the work intensity zones for the junior (13-14 year-olds’) radio direction finding sport.

Methods and structure of the study. Sampled for the study purposes were 8 radio direction finding competitors aged 13.5±0.5 years on average, with the radio direction finding sport records averaging 3.3±0.5 years; having the formal sport qualifications of Class I (n=1), Class II (n=4) and Class III (n=3) including three prospects for the Russian national team.

Tests under the study were designed to find the anaerobic (AnT) threshold rates in practical competitions in the 3.5MHz radio direction finding discipline. One week prior to the test event, the sample was tested for the individual AnT rates on a 200m outdoor track. Upon a warm-up time, the sample ran fifteen 200m circles with intensity rates raised in a stepped manner so that every next circle was run faster – with the athlete required to maintain the speed and avoid finishing spurts. The 1-circle speed was set at 10.5 km/h with 0.5 km/h accelerations in every next circle, with the athletes tested for blood lactate contents after circles 3, 6, 9, 12 and 15; and with HR tested after every circle. The HT and La test data profiles were used to find and analyze the extremes on the curves.

The blood lactate and HR variation tests were found highly beneficial as they allow profiling the run intensity zones and analyze/ manage the competitive and training process intensities in the radio direction finding sport. The blood lactate (La) was tested in the study by a mobile reflective photometer Accutrend Lactate (made by Roche Diagnostics GmbH, Germany) with application of colorimetric lactate-oxidizing reaction. The HR was tested by Polar (Finland-made) HR meter systems with the readings taken every second on the distance.

The test distance was 3750m long with the total ascend of 100m in a low- and mean-density forest, with the athletes required to locate 4 radio transmitters operating in 5min cycles (1min on and 4min off). Blood for the lactate tests was taken prior to the start, after the radio transmitter 1 and radio transmitter 3 locations (on the 1000m and 2350m marks with the 35m and 80m interim ascends, respectively) and straight after the finish, upon the 3750m race with the 100m ascend.

Results and discussion. We profiled the HR and blood lactate variations for a week prior to the AnT rating test run. The individual AnT rating test data were analyzed versus the commonly accepted blood lactate standard of 4 mmol/ l, with the AnT-level blood lactate content found to reach 4.1±0.2 mmol/l and HR 175.2±5.1 bpm, with the last figure being significantly higher than in the adult athletes as provided by the cyclic-sports-specific training/ competitive workload classification system by F.P. Suslov, V.N. Kulakov, 1986; V.A. Sirenko, 1990; G.N. Maximenko, V.G. Nikitushkin, 1990 et al. and substantiated by a few other studies [5, 4, 3]. Given in Table 1 hereunder are the sample’s blood lactate and HR variation data for the classical distance.


Table 1. Blood lactate and HR variation data of the sample (n=8) for the classical 3.5MHz radio direction finding distance, {C}




± σ

Test rates


Radio transmitter 1

Radio transmitter 3

Finishing span

Location moment

Start to radio transmitter 1

Location moment

Radio transmitter 1 to radio transmitter 3


Radio transmitter 2 to finish

Run distance, m




Cumulative ascend, m




HR, bpm















Lactate (La), mmol/ l 





Table 1 data demonstrate the HR and lactate test rates growing over the distance, with the average lactate contents at the radio transmitter 1 location moment coming to AnT of 4.5±0.5 mmol/l; and with the HR averaging 182.2±6.4 bpm. It should be mentioned that the HR at the radio transmitter 3 and radio transmitter 1 location moments are vertically the same (183.1±7.5 bpm) whilst the blood lactate levels are above the AnT (5.3±1.1 mmol/l). The highest test rates largely exceeding the AnT were found on the finish (HR = 194.3±6.7 bmp and La = 6.3±1.1 mmol/l); versus the interim HR test rates of 172.2±11.1 bmp in the Start to radio transmitter 1 section, 173.0±9.4 bpm in the radio transmitter 1 to radio transmitter 3 section and 174.9±9.7 bmp in radio transmitter 3 to Finish section – that are indicative of the workloads on the classical distance for this age group varying close to the AnT level.

Furthermore, our analysis of the classical-distance test data variations shows that the athletes may exceed the AnT in a few points. Thus the La and HR go beyond the AnT when the athletes accelerate as soon as the radio transmitter is located and in the final run-only section from the last radio transmitter to the finishing line.

The HR was tested by Polar (Finland-made) HR measurement systems with the readings taken every second on the distance, with the HR profiles showing most of the time on the distance (62%) taken by the aerobic ‘developmental’ energy supply mode with the HR varying within the range of 165‒185 bpm. The mixed aerobic-anaerobic and anaerobic work (with the HR >185 bmp and HR>195 bmp, respectively) were tested to account for 16.1% and 2.6% of the distance time, respectively; and 19.3% of the distance time was taken by the aerobic ‘rehabilitative’ mid-intensity work.

The test data profiles and analyses show the performance variations being driven by the cyclic operation of the radio transmitters as was mentioned before. This is the key reason for the HR data variations – as demonstrated, e.g., by the individual HR profile of one of the athletes: see Figure 1.

Figure 1. Individual HR variation data versus the AnT of 175.7 bmp


The HR were found to vary within the range of 172-205 bpm in between the radio transmitter (with the lowest HR of 141 bpm tested 1min after the start) due to the cyclic operation mode of the radio transmitter and the relevant tactical and technical actions of the athletes.

Conclusion. Based on the HR and blood lactate variation test data on the classical radio direction finding distance, we found the work mostly claiming the aerobic energy supply at the AnT level with some excesses in a few sections on the distance; with 62% of the time claimed by the aerobic ‘developmental’ intensity zone (with La = 4‒4.5 mmol/l; and HR =165–185 bmp). The mixed aerobic-anaerobic work zone (with La = 8‒10 mmol/l and HR = 185–195 bpm) was tested to claim 16.0% of the distance time. And the anaerobic ‘glycolytic’ intensity zone (with La >8‒10.0 mmol/l and HR>195 bpm) claiming only 2.3‒2.6% of the distance time dominated by the final run-only section. The performance tests and the La/ HR profiles with the intensity zone analyses for the classical RDF distances were proved beneficial for the training and competitive performance improvement purposes.



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  2. Zelensky K.G. Issledovanie kontsentratsii laktata v krovi u vysokokvalifitsirovannykh sportsmenov vo vremya prohozhdeniya distantsii v sportivnoy radiopelengatsii [Study of blood lactate concentration in highly skilled athletes when passing classic distance in radio direction finding]. Vestnik sportivnoy nauki, 2009, no. 6, pp. 44-46.

  3. Gaisl G, Buchberger J. The aerobic-anaerobic transition in sports pupils aged 10–11. Leistungssport. 1979. № 9: P. 202.

  4. Racazer J., Brehmer R. Znaczenie okrešlania progów przemian tlenowych I beztlenowych dla sterowania treningiem wytrzymalošciowym. Sport Wyczynowy. 1980. Vol. 4, no. 184. P. 3.

  5. Simon G., Berg A., Dickhuth H., Simonatl A. et al. Bestimmung der anaeroben Schwelle in Abhängigkeit von Alter und von der Leistungsfähigkeit. Dtsch Z Sportmed. 1981. 32: P. 7.

  6. Zelensky K.G. Competitive radio location process design at every stage of long-term training system.  Theory and Practice of Physical Culture. 2018. no. 4(960). P.66.


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The study found that the aerobic/ anaerobic-work-specific heart rates in the 13-14 year-old competitors in amateur radio direction finding (RDF) sport are higher than in adults. Sampled for the study purposes were 8 RDF competitors aged 13.5±0.5 years on average, with the RDF sport records averaging 3.3±0.5 years; having the following formal sport qualifications: Class I (n=1), Class II (n=4) and Class III (n=3) including three prospects for the Russian national team. Based on the HR and blood lactate (La) variation test data on the classical RDF distance, we found the following: run intensity of the sample is widely variable in the aerobic/ aerobic-anaerobic energy supply modes; blood lactate levels at the critical moments are somewhat above the anaerobic threshold and fall when the run intensity drops (as provided by the HR profiles) to the levels that make it possible for the young athletes to effectively compete.