Difference between revisions of "Dynamics of activation"

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(→‎Data for model validation, [H+])
 
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The rate of muscles ATP hydrolysis with a stepwise increase in external load increases almost immediately (as seen by the rate of ADP formation) (Broxterman et al., 2017 <cite>1</cite>; Bartlett et al., 2020 <cite>2</cite>):
 
The rate of muscles ATP hydrolysis with a stepwise increase in external load increases almost immediately (as seen by the rate of ADP formation) (Broxterman et al., 2017 <cite>1</cite>; Bartlett et al., 2020 <cite>2</cite>):
  
 +
  
−
[[File: Bartlett_2020,_Oxidative_ATP_synthesis_in_human_quadriceps_ADP.png | 800px | Changes in ADP (C) across time for each trial]]
+
[[File: Bartlett_2020,_Oxidative_ATP_synthesis_in_human_quadriceps_ADP.png | 500px | Changes in ADP (C) across time for each trial]]
  
 
Figure from (Bartlett et al., 2020) <cite>2</cite>, Changes in muscle ADP across time during trials.
 
Figure from (Bartlett et al., 2020) <cite>2</cite>, Changes in muscle ADP across time during trials.
 
    
 
    
−
[[File: Broxterman_2017,_Bioenergetics_and_ATP_Synthesis_during_Exercise.png | 800px | Intramuscular metabolic perturbation during high-intensity intermittent isometric single-leg knee-extensor exercise]]
+
[[File: Broxterman_2017,_Bioenergetics_and_ATP_Synthesis_during_Exercise.png | 600px | Intramuscular metabolic perturbation during high-intensity intermittent isometric single-leg knee-extensor exercise]]
  
 
Figure from (Broxterman et al., 2017) <cite>1</cite>, Changes in muscle ADP across time.
 
Figure from (Broxterman et al., 2017) <cite>1</cite>, Changes in muscle ADP across time.
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The rate of muscles PCr hydrolysis with a stepwise increase in external load increases almost immediately (Layec et al., 2008 <cite>3</cite>; Cannon et al., 2014 <cite>4</cite>; Fiedler et al., 2016 <cite>5</cite>; Broxterman et al., 2017 <cite>1</cite>; Bartlett et al., 2020 <cite>2</cite>).  
 
The rate of muscles PCr hydrolysis with a stepwise increase in external load increases almost immediately (Layec et al., 2008 <cite>3</cite>; Cannon et al., 2014 <cite>4</cite>; Fiedler et al., 2016 <cite>5</cite>; Broxterman et al., 2017 <cite>1</cite>; Bartlett et al., 2020 <cite>2</cite>).  
 +
 
   
 
   
−
[[File: Layec_2008,_Accurate_work-rate_measurements_during_in_vivo_MRS_studies_of_exercising_human_quadriceps_PCr | 800px | Changes in muscle PCr across time]]
+
[[File: Layec_2008,_Accurate_work-rate_measurements_during_in_vivo_MRS_studies_of_exercising_human_quadriceps_PCr | 400px | Changes in muscle PCr across time]]
  
−
Figure from (Layec et al., 2008) <cite>3</cite>, Changes in muscle PCr across time
+
Figure from (Layec et al., 2008) <cite>3</cite>, Changes in muscle PCr across time
 +
 
      
 
      
−
[[File: Bartlett_2020,_Oxidative_ATP_synthesis_in_human_quadriceps_PCr.png | 800px | Changes in PCr (A) across time for each trial]]
+
[[File: Bartlett_2020,_Oxidative_ATP_synthesis_in_human_quadriceps_PCr.png | 400px | Changes in PCr (A) across time for each trial]]
  
 
Figure from (Bartlett et al., 2020) <cite>2</cite>, Changes in muscle PCr across time during trials
 
Figure from (Bartlett et al., 2020) <cite>2</cite>, Changes in muscle PCr across time during trials
  
 
In tests with a stepwise increase in external load, the following dynamics of changes in the PCr concentration is observed (Schocke et al., 2005 <cite>6</cite>; Greiner et al., 2007 <cite>7</cite>).
 
In tests with a stepwise increase in external load, the following dynamics of changes in the PCr concentration is observed (Schocke et al., 2005 <cite>6</cite>; Greiner et al., 2007 <cite>7</cite>).
 +
 
   
 
   
−
[[File: Greiner_2007,_High-energy_phosphate_metabolism_in_the_calf_muscle_of_healthy_humans_PCr.png | 800px | Changes in PCr concentration across time]]
+
[[File: Greiner_2007,_High-energy_phosphate_metabolism_in_the_calf_muscle_of_healthy_humans_PCr.png | 500px | Changes in PCr concentration across time]]
  
 
Figure from (Greiner et al., 2007) <cite>7</cite>, changes in the PCr concentration across time
 
Figure from (Greiner et al., 2007) <cite>7</cite>, changes in the PCr concentration across time
 
    
 
    
−
[[File: Schocke_2005,_High-energy_phosphate_metabolism_during_calf_exercise_in_humans_PCr.png | 800px | Changes in PCr concentration across time]]
+
[[File: Schocke_2005,_High-energy_phosphate_metabolism_during_calf_exercise_in_humans_PCr.png | 500px | Changes in PCr concentration across time]]
  
 
Figure from (Schocke et al., 2005) <cite>6</cite>, changes in the PCr concentration across time
 
Figure from (Schocke et al., 2005) <cite>6</cite>, changes in the PCr concentration across time
 
According to those data, with a frequent stepwise increase or with a gradual increase in external load, the rate of PCr hydrolysis should be constant.
 
According to those data, with a frequent stepwise increase or with a gradual increase in external load, the rate of PCr hydrolysis should be constant.
  
 +
=== The rate of muscles glycolysis in general ===
  
−
=== The rate of muscles glycolysis in general ===
 
 
   
 
   
 
[[File: Larsen_2014,_High-Intensity_Interval_Training_Alters_ATP_Pathway_Flux_During_Maximal_Muscle_Contractions_in_Humans_Glycolisys.png | 800px | Rates of ATP synthesis during a 24-s maximal voluntary knee extension contraction]]
 
[[File: Larsen_2014,_High-Intensity_Interval_Training_Alters_ATP_Pathway_Flux_During_Maximal_Muscle_Contractions_in_Humans_Glycolisys.png | 800px | Rates of ATP synthesis during a 24-s maximal voluntary knee extension contraction]]
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Calculation of glycolytic ATP synthesis from (Larsen et al., 2014) <cite>8</cite>:
 
Calculation of glycolytic ATP synthesis from (Larsen et al., 2014) <cite>8</cite>:
  
−
[[File: Larsen_2014,_High-Intensity_Interval_Training_Alters_ATP_Pathway_Flux_During_Maximal_Muscle_Contractions_in_Humans_ Calulations.png | 800px | Calculation of glycolytic ATP synthesis]]
+
 +
 
 +
[[File: Larsen_2014,_High-Intensity_Interval_Training_Alters_ATP_Pathway_Flux_During_Maximal_Muscle_Contractions_in_Humans_ Calulations.png | 600px | Calculation of glycolytic ATP synthesis]]
 +
 
 
   
 
   
 
[[File: Layec_2015,_Impact_of_age_on_exercise-induced_ATP_supply_during_supramaximal_plantar_flexion_in_humans.png | 400px | The rate of ATP synthesis through anaerobic glycolysis (A), oxidative phosphorylation (B)]]
 
[[File: Layec_2015,_Impact_of_age_on_exercise-induced_ATP_supply_during_supramaximal_plantar_flexion_in_humans.png | 400px | The rate of ATP synthesis through anaerobic glycolysis (A), oxidative phosphorylation (B)]]
Line 54: Line 61:
 
Figure from (Layec et al., 2015) <cite>9</cite>, The rate of ATP synthesis through anaerobic glycolysis (A), oxidative phosphorylation (B)
 
Figure from (Layec et al., 2015) <cite>9</cite>, The rate of ATP synthesis through anaerobic glycolysis (A), oxidative phosphorylation (B)
  
−
[[File: Walter_1999,_In_vivo_ATP_synthesis_rates_in_single_human_muscles_during_high_intensity_exercise_Glycolysis.png | 800px | Glycogenolytic and glycolytic rates in the medial gastrocnemius during maximal rate exercise]]
+
 
 +
 
 +
[[File: Walter_1999,_In_vivo_ATP_synthesis_rates_in_single_human_muscles_during_high_intensity_exercise_Glycolysis.png | 600px | Glycogenolytic and glycolytic rates in the medial gastrocnemius during maximal rate exercise]]
  
 
Figure from (Walter et al., 1999) <cite>10</cite>, Glycogenolytic and glycolytic rates in the medial gastrocnemius during maximal rate exercise.
 
Figure from (Walter et al., 1999) <cite>10</cite>, Glycogenolytic and glycolytic rates in the medial gastrocnemius during maximal rate exercise.
Line 60: Line 69:
 
Calculation of glycolytic ATP synthesis from (Walter et al., 1999) <cite>10</cite>:
 
Calculation of glycolytic ATP synthesis from (Walter et al., 1999) <cite>10</cite>:
 
   
 
   
−
[[File: Walter_1999,_In_vivo_ATP_synthesis_rates_in_single_human_muscles_during_high_intensity_exercise_Calculations.png | 800px | Calculation of glycolytic ATP synthesis]]
 
  
 +
[[File: Walter_1999,_In_vivo_ATP_synthesis_rates_in_single_human_muscles_during_high_intensity_exercise_Calculations.png | 500px | Calculation of glycolytic ATP synthesis]]
  
 
=== Dynamics of the activity of some glycolytic enzymes ===
 
=== Dynamics of the activity of some glycolytic enzymes ===
Line 79: Line 88:
 
Glycogen phosphorylase and PDH activity increases within seconds (Parolin et al., 1999) <cite>12</cite>.  
 
Glycogen phosphorylase and PDH activity increases within seconds (Parolin et al., 1999) <cite>12</cite>.  
 
   
 
   
−
[[File: Parolin_1999,_Regulation_of_skeletal_muscle_glycogen_phosphorylase_and_PDH_during_maximal_intermittent_exercise.png | 600px | Regulation of skeletal muscle glycogen phosphorylase and PDH during maximal intermittent exercise]]
+
[[File: Parolin_1999,_Regulation_of_skeletal_muscle_glycogen_phosphorylase_and_PDH_during_maximal_intermittent_exercise.png | 400px | Regulation of skeletal muscle glycogen phosphorylase and PDH during maximal intermittent exercise]]
  
 
Figure from (Parolin et al., 1999) <cite>12</cite>, Regulation of skeletal muscle glycogen phosphorylase and PDH during maximal intermittent exercise.
 
Figure from (Parolin et al., 1999) <cite>12</cite>, Regulation of skeletal muscle glycogen phosphorylase and PDH during maximal intermittent exercise.
−
 
  
 
=== Dynamics of oxidative phosphorylation activity at the onset of exercise ===
 
=== Dynamics of oxidative phosphorylation activity at the onset of exercise ===
Line 88: Line 96:
 
Despite the sufficient amount of oxygen bound to myoglobin in the muscles, oxidative phosphorylation begins with some delay with a stepwise increase in load (Grassi et al., 2005 <cite>13</cite>; Richardson et al., 2015 <cite>14</cite>) with a time lag of about 10 seconds.
 
Despite the sufficient amount of oxygen bound to myoglobin in the muscles, oxidative phosphorylation begins with some delay with a stepwise increase in load (Grassi et al., 2005 <cite>13</cite>; Richardson et al., 2015 <cite>14</cite>) with a time lag of about 10 seconds.
 
   
 
   
−
[[File: Grassi_2005,_Delayed_Metabolic_Activation_of_Oxidative_Phosphorylation_in_Skeletal_Muscle_at_Exercise_Onset.png | 600px | Time courses of changes of deoxygenated Hb + Mb concentration, as well as of oxygenated Hb + Mb concentration]]
+
[[File: Grassi_2005,_Delayed_Metabolic_Activation_of_Oxidative_Phosphorylation_in_Skeletal_Muscle_at_Exercise_Onset.png | 400px | Time courses of changes of deoxygenated Hb + Mb concentration, as well as of oxygenated Hb + Mb concentration]]
  
 
Figure from (Grassi et al., 2005) <cite>13</cite>, Time courses of changes of deoxygenated Hb + Mb concentration, as well as of oxygenated Hb + Mb concentration.   
 
Figure from (Grassi et al., 2005) <cite>13</cite>, Time courses of changes of deoxygenated Hb + Mb concentration, as well as of oxygenated Hb + Mb concentration.   
 
    
 
    
−
[[File: Richardson_2015,_MRS_Evidence_of_Adequate_O2_Supply_in_Human_Skeletal_Muscle_at_the_Onset_of_Exercise.png | 600px | Tracing of the deoxygenated myoglobin (deoxy-Mb) signal at the onset of moderate-intensity exercise]]
+
[[File: Richardson_2015,_MRS_Evidence_of_Adequate_O2_Supply_in_Human_Skeletal_Muscle_at_the_Onset_of_Exercise.png | 400px | Tracing of the deoxygenated myoglobin (deoxy-Mb) signal at the onset of moderate-intensity exercise]]
  
 
Figure from (Richardson et al., 2015) <cite>14</cite>, Tracing of the deoxygenated myoglobin (deoxy-Mb) signal at the onset of moderate-intensity exercise.
 
Figure from (Richardson et al., 2015) <cite>14</cite>, Tracing of the deoxygenated myoglobin (deoxy-Mb) signal at the onset of moderate-intensity exercise.
Line 98: Line 106:
 
During repeated exercise, the oxygen-uptake rate increases faster compared to the first bout of exercise. This must be taken into account when modelling intermittent loads.
 
During repeated exercise, the oxygen-uptake rate increases faster compared to the first bout of exercise. This must be taken into account when modelling intermittent loads.
 
    
 
    
−
[[File: Bangsbo_2001,_ATP_production_and_efficiency_of_human_skeletal_muscle_during_intense_exercise,_effect_of_previous_exercise.png | 600px | Thigh oxygen uptake during EX1 and EX2]]
+
[[File: Bangsbo_2001,_ATP_production_and_efficiency_of_human_skeletal_muscle_during_intense_exercise,_effect_of_previous_exercise.png | 500px | Thigh oxygen uptake during EX1 and EX2]]
  
 
Figure from (Bangsbo et al., 2001) <cite>15</cite>, Thigh oxygen uptake during EX1 and EX2.
 
Figure from (Bangsbo et al., 2001) <cite>15</cite>, Thigh oxygen uptake during EX1 and EX2.
  
−
[[File: Combes_2016,_Effect_of_work-rest_cycle_duration_on_VO2_fluctuations_during_intermittent_exercise.png | 600px | VO2 fluctuations for each exercise transition]]
+
 +
[[File: Combes_2016,_Effect_of_work-rest_cycle_duration_on_VO2_fluctuations_during_intermittent_exercise.png | 400px | VO2 fluctuations for each exercise transition]]
  
 
Figure from (Combes et al., 2016) <cite>16</cite>, VO2 fluctuations for each exercise transition
 
Figure from (Combes et al., 2016) <cite>16</cite>, VO2 fluctuations for each exercise transition
  
 
=== Data for model validation, [H+] ===
 
=== Data for model validation, [H+] ===
 +
 
   
 
   
−
[[File: Hargreaves_1998,_Muscle_metabolites_and_performance_during_high-intensity,_intermittent_exercise_T2.png | 800px | Table 2]]
+
[[File: Hargreaves_1998,_Muscle_metabolites_and_performance_during_high-intensity,_intermittent_exercise_T2.png | 1000px | Table 2]]
  
 
Table from (Hargreaves et al., 1998) <cite>17</cite>.
 
Table from (Hargreaves et al., 1998) <cite>17</cite>.
 
    
 
    
−
[[File: Hargreaves_1998,_Muscle_metabolites_and_performance_during_high-intensity,_intermittent_exercise_T3.png | 800px | Table 3]]
+
[[File: Hargreaves_1998,_Muscle_metabolites_and_performance_during_high-intensity,_intermittent_exercise_T3.png | 500px | Table 3]]
  
 
Table from (Hargreaves et al., 1998) <cite>17</cite>.
 
Table from (Hargreaves et al., 1998) <cite>17</cite>.
  
−
[[File: Spriet_1989,_Muscle_glycogenolysis_and_H+_concentration_during_maximal_intermittent_cycling_F1.png | 500px | Schematic representation of experimental design]]
+
 
−
[[File: Spriet_1989,_Muscle_glycogenolysis_and_H+_concentration_during_maximal_intermittent_cycling_T2.png | 800px | Table 2]]
+
[[File: Spriet_1989,_Muscle_glycogenolysis_and_H+_concentration_during_maximal_intermittent_cycling_F1.png | 400px | Schematic representation of experimental design]]
 +
[[File: Spriet_1989,_Muscle_glycogenolysis_and_H+_concentration_during_maximal_intermittent_cycling_T2.png | 600px | Table 2]]
  
 
Figure and table from (Spriet et al., 1989) <cite>18</cite>, maximal cycling for 30 s, each separated by 4 min of rest
 
Figure and table from (Spriet et al., 1989) <cite>18</cite>, maximal cycling for 30 s, each separated by 4 min of rest
 
   
 
   
−
[[File: Davies_2017,_Dissociating_external_power_from_intramuscular_exercise_intensity_during_intermittent_bilateral_knee-extension_in_humans.png | 1000px | PCr and pH responses to intermittent or continuous exercise]]
+
[[File: Davies_2017,_Dissociating_external_power_from_intramuscular_exercise_intensity_during_intermittent_bilateral_knee-extension_in_humans.png | 800px | PCr and pH responses to intermittent or continuous exercise]]
  
 
Figure from (Davies et al., 2017) <cite>19</cite>, PCr and pH responses to intermittent or continuous exercise.
 
Figure from (Davies et al., 2017) <cite>19</cite>, PCr and pH responses to intermittent or continuous exercise.
  
−
[[File: Chidnok_2013,_Muscle_metabolic_responses_during_highintensity_intermittent_exercise.png | 600px | Muscle [PCr] and pH responses during high-intensity intermittent exercise]]
+
 +
[[File: Chidnok_2013,_Muscle_metabolic_responses_during_highintensity_intermittent_exercise.png | 400px | Muscle [PCr] and pH responses during high-intensity intermittent exercise]]
  
 
Figure from (Chidnok et al., 2013) <cite>20</cite>, Muscle [PCr] and pH responses during high-intensity intermittent exercise.
 
Figure from (Chidnok et al., 2013) <cite>20</cite>, Muscle [PCr] and pH responses during high-intensity intermittent exercise.
Line 131: Line 143:
 
Overall, MRS studies show pH recovery is too fast compared to studies that used biochemical pH measurements, see below.
 
Overall, MRS studies show pH recovery is too fast compared to studies that used biochemical pH measurements, see below.
 
    
 
    
−
[[File: Sahlin_1976,_Lactate_content_and_pH_in_muscle_obtained_after_dynamic_exercise_F2.png | 600px | Relationship between pH and content of lactate + pyruvate in muscle during recovery from exhaustive dynamic exercise]]
+
[[File: Sahlin_1976,_Lactate_content_and_pH_in_muscle_obtained_after_dynamic_exercise_F2.png | 400px | Relationship between pH and content of lactate + pyruvate in muscle during recovery from exhaustive dynamic exercise]]
 
[[File: Sahlin_1976,_Lactate_content_and_pH_in_muscle_obtained_after_dynamic_exercise_F3.png | 800px | Time courses of lactate content and pH in muscle samples taken during recovery from exhaustive dynamic exercise]]
 
[[File: Sahlin_1976,_Lactate_content_and_pH_in_muscle_obtained_after_dynamic_exercise_F3.png | 800px | Time courses of lactate content and pH in muscle samples taken during recovery from exhaustive dynamic exercise]]
  
 
Figures from (Sahlin et al., 1976) <cite>21</cite>,
 
Figures from (Sahlin et al., 1976) <cite>21</cite>,
  
−
[[File: Parolin_1999,_Regulation_of_skeletal_muscle_glycogen_phosphorylase_and_PDH_during_maximal_intermittent_exercise_T2.png | 800px | Muscle metabolite content in the vastus lateralis at rest and during maximal intermittent isokinetic cycling]]
+
 +
[[File: Parolin_1999,_Regulation_of_skeletal_muscle_glycogen_phosphorylase_and_PDH_during_maximal_intermittent_exercise_T2.png | 1000px | Muscle metabolite content in the vastus lateralis at rest and during maximal intermittent isokinetic cycling]]
  
 
Table from (Parolin et al., 1999) <cite>12</cite>.
 
Table from (Parolin et al., 1999) <cite>12</cite>.
 
   
 
   
−
[[File: Parolin_1999,_Regulation_of_skeletal_muscle_glycogen_phosphorylase_and_PDH_during_maximal_intermittent_exercise_F4.png | 800px | Muscle metabolite content in the vastus lateralis at rest and during maximal intermittent isokinetic cycling]]
+
[[File: Parolin_1999,_Regulation_of_skeletal_muscle_glycogen_phosphorylase_and_PDH_during_maximal_intermittent_exercise_F4.png | 400px | Muscle metabolite content in the vastus lateralis at rest and during maximal intermittent isokinetic cycling]]
  
 
Figure from (Parolin et al., 1999) <cite>12</cite>.
 
Figure from (Parolin et al., 1999) <cite>12</cite>.
 
    
 
    
−
[[File: Kushmerick_1992,_Regulation_of_oxygen_consumption_in_fast_and_slow-twitch_muscle_F2.png | 800px | The time courses of changes in intracellular pH during stimulation at the various rates for the biceps]]
+
[[File: Kushmerick_1992,_Regulation_of_oxygen_consumption_in_fast_and_slow-twitch_muscle_F2.png | 400px | The time courses of changes in intracellular pH during stimulation at the various rates for the biceps]]
−
[[File: Kushmerick_1992,_Regulation_of_oxygen_consumption_in_fast_and_slow-twitch_muscle_F3.png | 800px | The time courses of changes in intracellular pH during stimulation at the various rates for the soleus]]
+
[[File: Kushmerick_1992,_Regulation_of_oxygen_consumption_in_fast_and_slow-twitch_muscle_F3.png | 400px | The time courses of changes in intracellular pH during stimulation at the various rates for the soleus]]
  
 
Figures from (Kushmerick et al., 1992) <cite>12</cite>, Data from cat muscles, The time courses of changes in intracellular pH during stimulation at the various rates for the biceps and for the soleus.
 
Figures from (Kushmerick et al., 1992) <cite>12</cite>, Data from cat muscles, The time courses of changes in intracellular pH during stimulation at the various rates for the biceps and for the soleus.

Latest revision as of 22:24, 30 March 2021

For model validation, dynamics of activation, ATP, PCr, glycolysis, oxidative phosphorylation. Ver. 1.0.

The rate of muscles ATP hydrolysis

The rate of muscles ATP hydrolysis with a stepwise increase in external load increases almost immediately (as seen by the rate of ADP formation) (Broxterman et al., 2017 [1]; Bartlett et al., 2020 [2]):


Changes in ADP (C) across time for each trial

Figure from (Bartlett et al., 2020) [2], Changes in muscle ADP across time during trials.

Intramuscular metabolic perturbation during high-intensity intermittent isometric single-leg knee-extensor exercise

Figure from (Broxterman et al., 2017) [1], Changes in muscle ADP across time.


The rate of muscles PCr hydrolysis

The rate of muscles PCr hydrolysis with a stepwise increase in external load increases almost immediately (Layec et al., 2008 [3]; Cannon et al., 2014 [4]; Fiedler et al., 2016 [5]; Broxterman et al., 2017 [1]; Bartlett et al., 2020 [2]).


Changes in muscle PCr across time

Figure from (Layec et al., 2008) [3], Changes in muscle PCr across time


Changes in PCr (A) across time for each trial

Figure from (Bartlett et al., 2020) [2], Changes in muscle PCr across time during trials

In tests with a stepwise increase in external load, the following dynamics of changes in the PCr concentration is observed (Schocke et al., 2005 [6]; Greiner et al., 2007 [7]).


Changes in PCr concentration across time

Figure from (Greiner et al., 2007) [7], changes in the PCr concentration across time

Changes in PCr concentration across time

Figure from (Schocke et al., 2005) [6], changes in the PCr concentration across time According to those data, with a frequent stepwise increase or with a gradual increase in external load, the rate of PCr hydrolysis should be constant.

The rate of muscles glycolysis in general

Rates of ATP synthesis during a 24-s maximal voluntary knee extension contraction

Figure from (Larsen et al., 2014) [8], Rates of ATP synthesis during a 24-s maximal voluntary knee extension contraction (MVC), ATP provision from glycolysis (B, ATPGLY).

Calculation of glycolytic ATP synthesis from (Larsen et al., 2014) [8]:


Calculation of glycolytic ATP synthesis


The rate of ATP synthesis through anaerobic glycolysis (A), oxidative phosphorylation (B)

Figure from (Layec et al., 2015) [9], The rate of ATP synthesis through anaerobic glycolysis (A), oxidative phosphorylation (B)


Glycogenolytic and glycolytic rates in the medial gastrocnemius during maximal rate exercise

Figure from (Walter et al., 1999) [10], Glycogenolytic and glycolytic rates in the medial gastrocnemius during maximal rate exercise.

Calculation of glycolytic ATP synthesis from (Walter et al., 1999) [10]:


Calculation of glycolytic ATP synthesis

Dynamics of the activity of some glycolytic enzymes

Calcium-regulated PFK-1 activity increases almost instantly (Schmitz et al., 2013) [11].

PFK-1 (de)activation kinetics

Figure from (Schmitz et al., 2013) [11], PFK-1 (de)activation kinetics

The PFK-1 activity is regulated by metabolites also

The regulation of PFK-1

Figure from (Schmitz et al., 2013) [11], Schematic representation of the regulation of PFK-1 as modeled in each model configuration. Model configuration (B) represented the hypothesis in which binding of calcium-calmodulin complexes to PFK-1 partly reliefs ATP inhibition of the enzyme independent of the levels of ADP and AMP. Model configuration (C) represented the hypothesis in which binding of calcium-calmodulin complexes partly reliefs ATP inhibition by enhancing the competitive binding of AMP and ADP to the inhibitory ATP site.

Glycogen phosphorylase and PDH activity increases within seconds (Parolin et al., 1999) [12].

Regulation of skeletal muscle glycogen phosphorylase and PDH during maximal intermittent exercise

Figure from (Parolin et al., 1999) [12], Regulation of skeletal muscle glycogen phosphorylase and PDH during maximal intermittent exercise.

Dynamics of oxidative phosphorylation activity at the onset of exercise

Despite the sufficient amount of oxygen bound to myoglobin in the muscles, oxidative phosphorylation begins with some delay with a stepwise increase in load (Grassi et al., 2005 [13]; Richardson et al., 2015 [14]) with a time lag of about 10 seconds.

Time courses of changes of deoxygenated Hb + Mb concentration, as well as of oxygenated Hb + Mb concentration

Figure from (Grassi et al., 2005) [13], Time courses of changes of deoxygenated Hb + Mb concentration, as well as of oxygenated Hb + Mb concentration.

Tracing of the deoxygenated myoglobin (deoxy-Mb) signal at the onset of moderate-intensity exercise

Figure from (Richardson et al., 2015) [14], Tracing of the deoxygenated myoglobin (deoxy-Mb) signal at the onset of moderate-intensity exercise.

During repeated exercise, the oxygen-uptake rate increases faster compared to the first bout of exercise. This must be taken into account when modelling intermittent loads.

Thigh oxygen uptake during EX1 and EX2

Figure from (Bangsbo et al., 2001) [15], Thigh oxygen uptake during EX1 and EX2.


VO2 fluctuations for each exercise transition

Figure from (Combes et al., 2016) [16], VO2 fluctuations for each exercise transition

Data for model validation, [H+]

Table 2

Table from (Hargreaves et al., 1998) [17].

Table 3

Table from (Hargreaves et al., 1998) [17].


Schematic representation of experimental design Table 2

Figure and table from (Spriet et al., 1989) [18], maximal cycling for 30 s, each separated by 4 min of rest

PCr and pH responses to intermittent or continuous exercise

Figure from (Davies et al., 2017) [19], PCr and pH responses to intermittent or continuous exercise.


Muscle [PCr] and pH responses during high-intensity intermittent exercise

Figure from (Chidnok et al., 2013) [20], Muscle [PCr] and pH responses during high-intensity intermittent exercise.

Overall, MRS studies show pH recovery is too fast compared to studies that used biochemical pH measurements, see below.

Relationship between pH and content of lactate + pyruvate in muscle during recovery from exhaustive dynamic exercise Time courses of lactate content and pH in muscle samples taken during recovery from exhaustive dynamic exercise

Figures from (Sahlin et al., 1976) [21],


Muscle metabolite content in the vastus lateralis at rest and during maximal intermittent isokinetic cycling

Table from (Parolin et al., 1999) [12].

Muscle metabolite content in the vastus lateralis at rest and during maximal intermittent isokinetic cycling

Figure from (Parolin et al., 1999) [12].

The time courses of changes in intracellular pH during stimulation at the various rates for the biceps The time courses of changes in intracellular pH during stimulation at the various rates for the soleus

Figures from (Kushmerick et al., 1992) [12], Data from cat muscles, The time courses of changes in intracellular pH during stimulation at the various rates for the biceps and for the soleus.

References

  1. Broxterman RM, Layec G, Hureau TJ, Morgan DE, Bledsoe AD, Jessop JE, Amann M, and Richardson RS. Bioenergetics and ATP Synthesis during Exercise: Role of Group III/IV Muscle Afferents. Med Sci Sports Exerc. 2017 Dec;49(12):2404-2413. DOI:10.1249/MSS.0000000000001391 | PubMed ID:28767527 | HubMed [1]
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All Medline abstracts: PubMed | HubMed
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